"use strict"; const {Fragment: _Fragment, jsx: _jsx, jsxs: _jsxs} = arguments[0]; function _createMdxContent(props) { const _components = { a: "a", blockquote: "blockquote", br: "br", code: "code", del: "del", em: "em", figure: "figure", h1: "h1", h2: "h2", h3: "h3", img: "img", li: "li", ol: "ol", p: "p", pre: "pre", span: "span", strong: "strong", ul: "ul", ...props.components }; return _jsxs(_Fragment, { children: [_jsxs(_components.h1, { id: "학습-배경", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#학습-배경", children: _jsx(_components.span, { className: "icon icon-link" }) }), "학습 배경"] }), "\n", _jsxs(_components.p, { children: ["나는 리액트 이벤트에 ", _jsx(_components.code, { children: "onClick={...}" }), " ", _jsx(_components.code, { children: "()=> fn()" }), " 인라인 익명 콜백 함수를 사용한다. 이렇게 사용하는 이유는 map을 이용해 배열을 순회하여 item을 ", _jsx(_components.code, { children: "fn()" }), " 함수로 넘겨줄 때 ", _jsx(_components.code, { children: "onClick={fn(item)}" }), " 으로 사용할 수 없기 때문이다. ", _jsx(_components.code, { children: "onClick={fn(item)}" }), " 를 사용하게 되면 ", _jsx(_components.code, { children: "fn()" }), " 함수가 바로 실행되어 기대했던 상황이 아닌 디버깅부터 시작해야 한다…"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{()=> " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")}" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 위처럼 사용!" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// map으로 출력하는 item 매개변수를 받기 위해서 ()=> 익명 함수를 열고 " }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// handleClick(item) 콜백함수로 변수를 받는다." }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")}" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 바로 실행됨!" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// handleClick() 콜백 함수를 호출하는 ()가 있어서 바로 실행됨." }) })] }) }) }), "\n", _jsx(_components.p, { children: "그러던 도중, 과제를 수행하다가 PR에 조원분이 리뷰하며 쓴 글을 보게 되었다. 익명 함수가 메모리를 더 잡아먹기에 좋지 않다는 걸 배웠다는 내용이었다. 정말 그런가? 콜백함수를 이벤트에 바인딩 할 때 그런 것까지 신경써본 적이 없었다. 궁금한 찰나에 직접 조사해보기로 결심하고 해당 글을 써봤다." }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsx(_components.p, { children: "틀린 내용이 있을 수도 있고, 시간이 지나 생각이 바뀔 수도 있지만 내가 조사하며 추론한 결과는 아래와 같았다…!" }), "\n"] }), "\n", _jsxs(_components.h2, { id: "학습-및-조사-전-결과-예상", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#학습-및-조사-전-결과-예상", children: _jsx(_components.span, { className: "icon icon-link" }) }), "학습 및 조사 전 결과 예상"] }), "\n", _jsx(_components.p, { children: "인라인 익명 함수가 가장 많은 메모리를 사용할 것 같다. 그리고 고차 함수, 인라인 콜백 함수, 일반적인 콜백 함수 순으로 메모리를 사용하지 않을까?" }), "\n", _jsx(_components.p, { children: "익명 함수는 리렌더링 마다 함수 객체를 새롭게 만들어 실행하기 때문에 가장 많을 것이다. 고차 함수 또한, 중간에 익명 함수가 포함되어 있으니 마찬가지로 내부 함수는 새로운 함수 객체를 생성하여 메모리를 잡아 먹을 것이다." }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "익명 함수 > 고차 함수 > 익명 콜백 함수 > 콜백 함수" }) }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.em, { children: "그렇다면, 내 추측이 맞는지 확인해보러 가자. 아래의 내용은 어디까지나 리액트 환경에서 조사해본 것이다. 리액트를 사용하지 않는 순수 자바스크립트 환경에서는 다를 수 있다." }) }), "\n", _jsxs(_components.h1, { id: "onclick--fn-같은-방식이-onclickfn-보다-메모리를-더-사용하게-되는-이유", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#onclick--fn-같은-방식이-onclickfn-보다-메모리를-더-사용하게-되는-이유", children: _jsx(_components.span, { className: "icon icon-link" }) }), _jsx(_components.code, { children: "onClick={() => fn()}" }), " 같은 방식이 ", _jsx(_components.code, { children: "onClick={fn}" }), " 보다 메모리를 더 사용하게 되는 이유"] }), "\n", _jsx(_components.p, { children: "제목에서 알 수 있듯이, 일반적인 콜백 함수보다 익명 콜백 함수가 메모리를 더 사용한다. 그 이유가 뭘까?" }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{() => " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "fn" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "()}" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 본 게시글에서는 위와 같은 사용법을 인라인 익명 콜백 함수라 부를 예정이다." }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 정확히 어떤 명칭을 써야하는지 모르겠음." }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{fn}" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 위의 함수 사용은 일반적인 콜백 함수라 지칭하겠다." }) })] }) }) }), "\n", _jsx(_components.p, { children: "이유를 살펴보면, 리액트에서 동작하는 과정과 연관이 있는데, 컴포넌트가 (리)렌더링 될 때마다 새로운 함수 객체를 생성한다. 리액트에서는 익명함수를 같은 객체라고 판단하지 않기 때문에 매번 (리)렌더링 때마다 새롭게 선언되고 연산하기 때문에 메모리가 낭비된다." }), "\n", _jsxs(_components.h2, { id: "렌더링마다-함수-객체를-생성하나요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#렌더링마다-함수-객체를-생성하나요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "렌더링마다 함수 객체를 생성하나요?"] }), "\n", _jsxs(_components.h2, { id: "-onclickhandleclick", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#-onclickhandleclick", children: _jsx(_components.span, { className: "icon icon-link" }) }), "🚀 ", _jsx(_components.code, { children: "onClick={handleClick}" })] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "javascript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "javascript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " MyComponent" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Button clicked!\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Click Me;" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsxs(_components.p, { children: [_jsx(_components.code, { children: "handleClick" }), " 은 컴포넌트가 리렌더링 되어도 동일한 함수 객체를 사용한다. 같은 메모리 주소를 사용하기 때문에 새로운 함수 객체를 생성하지 않는다. 따라서 메모리를 추가적으로 낭비하지 않는다."] }), "\n", _jsxs(_components.h2, { id: "onclick--fn", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#onclick--fn", children: _jsx(_components.span, { className: "icon icon-link" }) }), "🚀 ", _jsx(_components.code, { children: "onClick={() => fn()}" })] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "javascript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "javascript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " MyComponent" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Button clicked!\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Click Me;" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsxs(_components.p, { children: [_jsx(_components.code, { children: "onClick" }), "에 걸린 함수는 익명으로 선언되었다. 이전에 렌더링에서 생성했던 함수와 다른 함수로 판단하여 함수 객체를 새롭게 정의한다. 컴포넌트가 리렌더링 될 때마다 새롭게 함수 객체가 정의되고 이는 메모리 낭비로 이어진다."] }), "\n", _jsxs(_components.h2, { id: "인라인-익명-함수라서-재정의-되는-건가요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#인라인-익명-함수라서-재정의-되는-건가요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "인라인 익명 함수라서 재정의 되는 건가요?"] }), "\n", _jsx(_components.p, { children: "익명 함수이기에 재정의 되는 것이 맞다. 조금 더 자세히 들어가보자면, 이름이 선언된 함수는 같은 메모리 주소를 사용한다. 리렌더링이 되어도 함수 이름을 통해 메모리에서 같은 참조를 유지할 수 있는 것이다." }), "\n", _jsx(_components.p, { children: "익명 함수는 함수 이름이 없어, 같은 메모리를 참조할 수 없고, 때문에 리렌더링 때마다 새롭게 함수 객체를 생성한다. 이전 렌더링의 익명 함수와 별개의 함수로 인식되며, 메모리의 낭비로 이어진다." }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsx(_components.p, { children: "중요한 것은 화살표 함수를 사용하는 데서 비롯된 것이 아니다. 모든 렌더링에서 새롭게 함수 객체를 생성하는 것에 있다." }), "\n"] }), "\n", _jsxs(_components.h2, { id: "왜-메모리가-낭비될까요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#왜-메모리가-낭비될까요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "왜 메모리가 낭비될까요?"] }), "\n", _jsxs(_components.p, { children: ["JavaScript는 새로운 함수 객체를 만들 때마다 새로운 메모리 공간을 할당한다. 이전 렌더링에서 생성된 함수는 더 이상 사용되지 않지만, GC(가비지 콜렉터)가 수집할 때까지 메모리 공간을 차지한 상태로 존재하게 된다. 이렇게 ", _jsx(_components.strong, { children: "리렌더링 때마다 생성된 함수 객체가 쌓이면서 메모리 낭비가 발생한다. 또한, 그렇게 생성된 메모리 공간을 가비지 콜렉터가 수집하면서 빈번한 수집이 일어나고 성능 저하가 발생할 수 있다." })] }), "\n", _jsxs(_components.p, { children: ["리액트는 렌더링마다 onClick에 할당된 함수가 이전과 같은지 체크한다. ", _jsx(_components.strong, { children: "익명 함수는 렌더링마다 새로운 함수 객체이므로 리액트는 항상 변경되었다고 판단하게 되는데, 결국 불필요한 Virtual DOM 업데이트가 발생할 가능성이 높아진다." })] }), "\n", _jsxs(_components.h2, { id: "그렇다면-무조건-인라인-익명-함수를-피해야-하나요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#그렇다면-무조건-인라인-익명-함수를-피해야-하나요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "그렇다면 무조건 인라인 익명 함수를 피해야 하나요?"] }), "\n", _jsxs(_components.p, { children: ["꼭 그렇지만도 않다. 인라인 익명 함수를 사용하지 않는 것은 성급한 최적화라는 시선이 있는데, 인라인 익명 함수가 성능에 문제가 되는 것을 증명하지 않고도 성능에 문제가 되니 사용하지 말자 라는 것은 성급하다는 의견이다. 또, useCallback, useMemo를 사용하는 것보다 인라인 익명 함수를 전달하는 것이 더 나은 경우도 있다고 한다. 실무에서 사용하는 컴포넌트가 순수 컴포넌트인 경우는 드물기 때문이다. 그리고 성능을 최적화하는 데 쓰이는 코드에는 비용이 따른다. 정확히, ", _jsx("u", { children: "모든 라인의 코드에는 비용이 든다." })] }), "\n", _jsxs(_components.h3, { id: "usecallback-usememo를-사용하면-되잖아요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#usecallback-usememo를-사용하면-되잖아요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "useCallback, useMemo를 사용하면 되잖아요?"] }), "\n", _jsx(_components.p, { children: "간단한 예시를 보며, 생각해보자." }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { useState, useCallback } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Counter" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "count" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "] " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useState" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "0" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "((" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "prev" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " prev " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "+" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") }" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // useCallback이 없다면 간단히 끝남" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useCallback" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "((" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "prev" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " prev " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "+" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, []); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 불필요한 종속성과 성급한 최적화" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "button" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}>Increment" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" }) })] }) }) }), "\n", _jsx(_components.p, { children: "버튼을 누르면 count를 증가시킨다." }), "\n", _jsx(_components.p, { children: "앞서 말했듯이 모든 라인에는 비용이 따른다. useCallback은 최적화를 위한 함수이지만, 내부적으로 메모리와 CPU 연산을 사용한다. 즉, 성능을 최적화 하기 위한 동작을 추가적으로 진행하는 것이다. 이걸로 useCallback을 사용하지 않았을 때보다 더 많은 연산을 하게 되는데, 함수 생성 비용이 낮다면, 혹은 연산이 가볍다면 useCallback을 사용하지 않는 것이 좋다." }), "\n", _jsx(_components.p, { children: "일반적으로, 리액트 컴포넌트가 리렌더링되면, 기존 함수는 GC에 의해 제거되고 새로운 함수 객체가 생성된다. 즉, 기존 함수 객체는 메모리에서 해제되므로 불필요한 점유가 발생하지 않는다. 따라서 메모리 낭비가 적은 반면에." }), "\n", _jsx(_components.p, { children: "useCallback을 사용하면 기존 함수 객체를 메모리에 유지하려고 하며, useCallback의 의존성이 변경될 경우 객체가 생성되면서 기존 함수도 그대로 유지된다. 따라서, 이전에 생성한 함수가 제거되지 않고 새로운 함수가 생성되어 메모리에 쌓인다." }), "\n", _jsx(_components.p, { children: "이전 함수가 참조되며, 보관하는 과정에서 이전 함수 객체도 계속 유지될 가능성이 있다. useCallback은 이전 함수 뿐만 아니라 의존성 배열의 값도 저장하고 비교해야 하는데, 이 과정에서 의존성 배열의 크기가 크거나 깊은 객체가 포함되어 있다면 오히려 성능에 좋지 않을 수 있다." }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsx(_components.p, { children: "useCallback은 리렌더링 최적화에는 효과적일 수 있으나 메모리 최적화에 항상 좋은 것이 아니다!" }), "\n"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { useState, useMemo } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " App" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "count" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "] " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useState" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "0" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " computedValue" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useMemo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " count " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "*" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "; " })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, [count]); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 불필요한 useMemo 사용" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "p" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Computed " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "Value" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ":" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "computedValue" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{() => " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "count" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " + 1)}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "Increment" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " " })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " );" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" }) })] }) }) }), "\n", _jsx(_components.p, { children: "useMemo는 CPU 연산이 큰 계산 결과를 저장하고 재사용하는 것이 목적이다. 의존성이 변하지 않았다면, 새로운 계산을 하지 않고 기존에 계산된 값을 사용한다. 그러나 useCallback과 동일하게, 예시의 코드는 큰 계산을 필요로 하지 않는다." }), "\n", _jsx(_components.p, { children: "useMemo를 사용함으로써 이전 값과 비교하는 비용이 추가되며, 연산 비용보다 비교 비용이 더 나간다면, useMemo 없이 사용하는 것이 더 효율적이다. useMemo를 변하지 않는 배열 정의에 사용할 수도 있겠다. 그러나 이 경우에는 리액트 컴포넌트의 바깥으로 빼내어 배열이 계속 선언되지 않도록 할 수도 있다. (모든 상황에서 그러할 수는 없겠지만)" }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { useState, useMemo } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " list" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"변하지\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"않는\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"배열\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "];" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 2. 이렇게 사용하는 편이 연산 비용없이 효율적일 수도 있다." }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " App" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " list" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useMemo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"변하지\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"않는\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"배열\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "], []);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // 1. 이렇게 사용할 수도 있으나..." }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "p" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Computed " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "Value" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ":" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "computedValue" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{() => " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "setCount" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "count" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " + 1)}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "Increment" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " " })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " );" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "그렇다면-언제-사용해야-하나요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#그렇다면-언제-사용해야-하나요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "그렇다면, 언제 사용해야 하나요?"] }), "\n", _jsxs(_components.p, { children: ["Kent.C.Dodds 개발자가 말하기를, ", _jsx(_components.strong, { children: "참조 동일성, 비용이 많이 드는 계산" }), "에 사용할 수 있다고 했다. 아래의 코드는 Kent.C.Dodds 개발자가 작성한 블로그에서 내용을 가져왔다."] }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://kentcdodds.com/blog/usememo-and-usecallback", children: "https://kentcdodds.com/blog/usememo-and-usecallback" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Foo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "({ " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }) {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " options" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { bar, baz };" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useEffect" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " buzz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(options);" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, [options]); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// we want this to re-run if bar or baz change" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">foobar" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Blub" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "Foo" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "=" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"bar value\"" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "} />;" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "코드를 보면, useEffect의 종속성에 options 변수가 들어있다. 매 렌더링마다 useEffect는 options가 변경이 되었는지 참조 동일성 체크를 하게 될 것이다. 그런데 options는 객체이고 렌더링마다 새롭게 정의된다. 이전 options와 현재 options가 다른 메모리 주소를 갖는 것이다. 그렇다면, useEffect는 options가 달라졌다고 판단하고 렌더 되는 순간마다 호출이 된다." }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// option 1" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Foo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "({ " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }) {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useEffect" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " options" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { bar, baz };" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " buzz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(options);" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, [bar, baz]); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// we want this to re-run if bar or baz change" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">foobar" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "위처럼 수정할 수도 있을 것이다. 그러나 객체, 배열, 함수처럼 참조 타입이 들어오는 경우는 어떻게 하면 좋을까?" }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Foo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "({ " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }) {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useEffect" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " options" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { bar, baz };" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " buzz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(options);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, [bar, baz]);" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">foobar" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Blub" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, 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}), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "], []);" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "Foo" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "bar" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "} " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "baz" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "} />;" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "이때 useCallback, useMemo를 사용할 수 있는 것이다. 그 외에도, useMemo를 활용한 예시를 찾아볼 수 있다." }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: 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children: "button" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "onClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}>{count}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " DualCounter" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", 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color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " increment2" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " setCount2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "((" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "c" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " c " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "+" }), 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"\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "두 개의 버튼이 있다. 둘 중 하나를 클릭하여 count의 상태가 변경되면, DualCounter 컴포넌트는 리렌더링 될 것이다. 리액트에서는 부모 컴포넌트가 변경되어 리렌더링 되면, 모든 자식 컴포넌트 또한 리렌더링 된다. 자식 컴포넌트에서는 변경이 일어나지 않더라도 말이다. 효율적인 코드라면, 클릭한 함수의 컴포넌트만 변경되는 것이 맞지 않을까?" }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " CountButton" }), 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"() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "count1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "setCount1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "] " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useState" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "0" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")" })] }), "\n", 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color: "#F47067" }, children: "+" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "), [])" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " [" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "count2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "setCount2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "] " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useState" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "0" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " increment2" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "useCallback" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " setCount2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "c" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " c " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "+" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 1" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "), [])" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#F47067" }, children: " <>" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "CountButton count" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{count1} onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{increment1} " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "/>" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "CountButton count" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{count2} onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{increment2} " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "/>" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#F47067" }, children: " " }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " )" }) })] }) }) }), "\n", _jsx(_components.p, { children: "React.memo를 사용하여 props가 변경될 때만 리렌더링을 시도할 것이다. 또한, props로 함수 객체를 전달하고 있는데, 이걸 useCallback으로 감싸서 전달한다면, 더욱더 불필요한 리렌더를 방지할 수 있다." }), "\n", _jsx(_components.p, { children: "또한 useMemo는 연산 비용이 큰 계산에도 효과적이다. 계산기, 배열, 정렬 등 연산하는 데 있어 많은 비용을 소모하는 로직은 useMemo를 사용할 수 있다." }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsxs(_components.p, { children: ["그러나 어디까지나 성능 최적화에는 비용이 든다. 아무런 기준 없이 사용하는 것을 반대하는 개발자들도 많으니 연산 비용, 생성 비용을 고려해서 실제 성능을 측정한 뒤, 최적화를 시도해도 늦지 않는다는 의견이 많고, 나 또한 그게 맞지 않을까 싶은 입장이다. 할 수 있는 건 하되, 성능을 고려한다고 useCallback, useMemo를 남용하는 것은 좋지 않다.", _jsx(_components.br, {}), "\n", "관련 글"] }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://legacy.reactjs.org/docs/hooks-faq.html#are-hooks-slow-because-of-creating-functions-in-render", children: "https://legacy.reactjs.org/docs/hooks-faq.html#are-hooks-slow-because-of-creating-functions-in-render" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://medium.com/@ryanflorence/react-inline-functions-and-performance-bdff784f5578", children: "https://medium.com/@ryanflorence/react-inline-functions-and-performance-bdff784f5578" }) }), "\n"] }), "\n", _jsxs(_components.h1, { id: "어떤-방식으로-코드의-메모리-비용을-줄일-수-있을까요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#어떤-방식으로-코드의-메모리-비용을-줄일-수-있을까요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "어떤 방식으로 코드의 메모리 비용을 줄일 수 있을까요?"] }), "\n", _jsxs(_components.ol, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "React.memo" }), "와 ", _jsx(_components.code, { children: "PureComponent" }), " 사용"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "useCallback" }), ", ", _jsx(_components.code, { children: "useMemo" }), " 사용"] }), "\n", _jsx(_components.li, { children: "익명 함수 피하기" }), "\n", _jsx(_components.li, { children: "객체 리터럴 피하기(객체(오브젝트)를 인라인으로 넣는 걸 다시 고려해보세요.)" }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "React.lazy" }), "와 ", _jsx(_components.code, { children: "React.Suspense" }), " 사용 (코드 스플리팅)"] }), "\n"] }), "\n", _jsxs(_components.h2, { id: "1️⃣reactmemo와-purecomponent-사용", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#1️⃣reactmemo와-purecomponent-사용", children: _jsx(_components.span, { className: "icon icon-link" }) }), "1️⃣ React.memo와 PureComponent 사용"] }), "\n", _jsx(_components.p, { children: "부모 컴포넌트가 리렌더링되면, 자식 컴포넌트들도 함께 리렌더링된다. 자식 컴포넌트의 props가 변하지 않았더라도 다시 렌더링되는 데 이때 사용할 수 있는 것이 React.memo, PureComponent이다." }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 함수형 컴포넌트" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { memo } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// ❌ 일반 컴포넌트" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " ComponentB" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "props" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">{props.propB}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// ✅ memo 적용 (성능 최적화)" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " ComponentB" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "memo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "((" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "props" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">{props.propB}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "});" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 클래스형 컴포넌트" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { Component, PureComponent } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// ❌ 일반 클래스 컴포넌트" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "class" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " ComponentB" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " extends" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " Component" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " render" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">{this.props.propB}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// ✅ PureComponent 적용 (성능 최적화)" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "class" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " ComponentB" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " extends" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " PureComponent" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#DCBDFB" }, children: " render" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">{this.props.propB}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsxs(_components.p, { children: ["위처럼 memo를 사용한다면, props가 변경되지 않는 한 자식 컴포넌트가 렌더링되는 일은 없어진다. 그러나 ", _jsx("u", { children: "이전 props와 새로운 props를 비교해야 하기 때문에 props가 크면 오히려 성능 저하가 될 수 있다. 특히, 컴포넌트를 props로 전달하게 되면, 비교 비용이 커질 수 있다." })] }), "\n", _jsxs(_components.h2, { id: "2️⃣usecallback-usememo-사용", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#2️⃣usecallback-usememo-사용", children: _jsx(_components.span, { className: "icon icon-link" }) }), "2️⃣ useCallback, useMemo 사용"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// useCallback" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { useCallback } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " MyComponent" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useCallback" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Button clicked!\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, []); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 의존성 배열이 비어 있으므로, 처음 생성된 함수 객체를 재사용함." })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "button" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "={" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}>Click me" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// useMemo" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { useMemo } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " MyComponent" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "({ " }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "num" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }) {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " result" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useMemo" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Calculating...\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " num " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "*" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " 2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "; " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// num이 변경될 때만 계산됨." })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, [num]); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// num이 변경될 때만 계산을 다시 실행" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Result: {result}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "예시에서 useCallback은 초기 렌더링 시 한 번만 생성되고 이후에도 같은 함수 객체를 사용한다. useMemo 또한, 종속성 배열의 num이 변경될 때만 계산을 다시 실행하게 되므로 메모리를 아낄 수 있다." }), "\n", _jsx("u", { children: "그러나 앞서 설명한대로 최적화를 위한 비교 연산 비용보다 생성 비용이 더 저렴하다면, 새롭게 생성하는 편이 메모리 최적화에 더 도움이 될 것이다." }), "\n", _jsxs(_components.h2, { id: "3️⃣익명-함수-피하기", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#3️⃣익명-함수-피하기", children: _jsx(_components.span, { className: "icon icon-link" }) }), "3️⃣ 익명 함수 피하기"] }), "\n", _jsx(_components.p, { children: "익명 함수를 피하기 위해 네이밍 함수를 사용할 수 있다. 혹은 useCallback을 사용하여 이전 함수를 재사용할 수 있다. 그러나 앞서 살펴본 것처럼 useCallback을 섣불리 사용함으로써 이전값과 비교하는 연산으로 인해 메모리를 더 잡아먹을 수도 있다는 걸 고려해야 한다." }), "\n", _jsxs(_components.h3, { id: "인라인-함수를-사용하는-다양한-방법", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#인라인-함수를-사용하는-다양한-방법", children: _jsx(_components.span, { className: "icon icon-link" }) }), "인라인 함수를 사용하는 다양한 방법"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "javascript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "javascript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Click " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 기본적인 사용" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(item.id)" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">Click " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 매개변수 전달이 필요할 때" })] })] }) }) }), "\n", _jsx(_components.p, { children: "나는 리액트에서 함수가 매개변수를 받을 때(이벤트 객체가 아닌) 위처럼 사용한다. 익명 화살표 함수를 만들고, 콜백함수를 반환하는 방식이다." }), "\n", _jsxs(_components.p, { children: ["그러나 리액트에서 사용하는 기본 방식은 첫번째 라인인데, ", _jsx(_components.code, { children: "()" }), " 호출을 붙이지 않는 까닭은 바로 실행됨을 방지하기 위해서다. click 이벤트가 발생했을 때만 함수가 실행되어야 하는데, ", _jsx(_components.code, { children: "()" }), " 를 붙여 ", _jsx(_components.code, { children: "handleClick()" }), " 로 작성하면, 컴포넌트가 생성되고 콜백함수는 바로 실행된다."] }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsxs(_components.p, { children: ["Vue는 리액트와 반대로 ", _jsx(_components.code, { children: "handleClick()" }), "를 작성해야 동작하는 걸로 알고 있다."] }), "\n"] }), "\n", _jsxs(_components.h3, { id: "그렇다면-매개변수를-전달하기-위해서-어떤-방식을-사용해야-할까", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#그렇다면-매개변수를-전달하기-위해서-어떤-방식을-사용해야-할까", children: _jsx(_components.span, { className: "icon icon-link" }) }), "그렇다면, 매개변수를 전달하기 위해서 어떤 방식을 사용해야 할까?"] }), "\n", _jsxs(_components.p, { children: ["과제를 수행하며 다른 사람의 코드를 리뷰할 수 있는 건, 큰 기회인 것 같다. 새로운 시각을 가져다주기 때문인데, 어떤 분께서 고차함수를 이용하여 사용하는 것을 봤었다. ", _jsx(_components.code, { children: "onClick={handleClick(item)}" }), " 처럼 사용하고 계셔서 처음에는 이게 바로 실행되지 않을까 싶었다. 조금 더 코드를 살펴보니 고차 함수이기 때문에 바로 실행되지 않는 것이었다. 실행을 하기 위해서는 ", _jsx(_components.code, { children: "handleClick()()" }), " 호출을 두번 선언해야한다."] }), "\n", _jsx(_components.p, { children: "그런데 고차 함수를 사용하는 것이 하나의 방법이었다. 매개변수를 전달하기 위해서 익명 함수로 콜백 함수를 넘기는 것이 아니라 고차 함수를 사용하여 매개변수를 넘기는 것이다." }), "\n", _jsxs(_components.p, { children: ["그러면, 고차 함수의 메모리 사용은 어떨까. 익명 함수와 비교했을 때 어느 정도를 사용하게 될까? 고차 함수도 내부 함수는 익명으로 선언되지 않나? ", _jsx(_components.code, { children: "const fn = () => () => ..." }), " 그래서 직접 실험해보기로 했다."] }), "\n", _jsxs(_components.h3, { id: "실험-내역", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#실험-내역", children: _jsx(_components.span, { className: "icon icon-link" }) }), "실험 내역"] }), "\n", _jsx(_components.p, { children: "동일한 환경에서 테스트 해보았다. 코드는 아래처럼 작성했고, 리액트에서 실험했기 때문에 부차적인 오류가 있을 수 있다. 하나의 탭을 띄우고 버튼을 5번 눌러보았다. 실험이 완료된 탭은 자료 캡쳐 후 제거하고 새로운 탭을 열어 동일하게 실험했다." }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "javascript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "javascript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " new" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " Array" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "1000000" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "fill" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'test'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "); " }), _jsx(_components.span, { style: { color: "#768390" }, children: "// 100만 개의 문자열 배열 생성" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // 1️⃣ 네이밍된 콜백 함수" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'콜백 함수 실행'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " data" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "();" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "`데이터 크기: ${" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "data" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "." }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "length" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "}`" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // 2️⃣ 인라인 익명 함수 (onClick={()=> handleClickHighOrder()})" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClickInline" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'콜백 함수 실행'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " data" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "();" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "`데이터 크기: ${" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "data" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "." }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "length" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "}`" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // 3️⃣ 고차 함수 (onClick={handleClickHighOrder()})" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClickHighOrder" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'고차 함수 실행'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " data" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "();" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "`데이터 크기: ${" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "data" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "." }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "length" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "}`" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // 4️⃣ `useCallback`으로 최적화된 콜백 함수" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " handleClickUseCallback" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useCallback" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'useCallback 함수 실행'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " data" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "();" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "`데이터 크기: ${" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "data" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "." }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "length" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "}`" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, []);" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: " // ✅ (메모리 체크)" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " checkMemoryUsage" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " if" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (window.performance " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "&&" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " window.performance.memory) {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'🧠 현재 메모리 상태:'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", window.performance.memory);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" }) }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " {" }), _jsx(_components.span, { style: { color: "#768390" }, children: "/* 1️⃣ 일반 콜백 함수 */" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">콜백 함수" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " {" }), _jsx(_components.span, { style: { color: "#768390" }, children: "/* 2️⃣ 인라인 익명 함수 */" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClickInline" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "()" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">인라인 익명 콜백 함수" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " {" }), _jsx(_components.span, { style: { color: "#768390" }, children: "/* 3️⃣ 고차 함수 */" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClickHighOrder" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "()" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">고차 함수" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " {" }), _jsx(_components.span, { style: { color: "#768390" }, children: "/* 4️⃣ useCallback 최적화 */" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "handleClickUseCallback" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">useCallback 함수" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "'()=> {} 인라인 익명 함수'" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " data" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " generateLargeArray" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "();" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "`데이터 크기: ${" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "data" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "." }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "length" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "}`" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ");" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " >" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " 인라인 익명 함수" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " {" }), _jsx(_components.span, { style: { color: "#768390" }, children: "/* ✅ 메모리 사용량 체크 */" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "button" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "checkMemoryUsage" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">메모리 체크" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "br" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " );" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "일반-콜백-함수-onclickhandleclick", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#일반-콜백-함수-onclickhandleclick", children: _jsx(_components.span, { className: "icon icon-link" }) }), "일반 콜백 함수 ", _jsx(_components.code, { children: "onClick={handleClick}>" })] }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 누르기 전" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 4GB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "7083405" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 6.75MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5524981" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 5.27MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "187" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 5번 누른 후" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 4GB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "11113885" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t10.60 MB = 3.85 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "9651361" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 9.20 MB = 3.93 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "293" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "//= 106 KB 차이" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "인라인-익명-콜백-함수-onclick--handleclickinline", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#인라인-익명-콜백-함수-onclick--handleclickinline", children: _jsx(_components.span, { className: "icon icon-link" }) }), "인라인 익명 콜백 함수 ", _jsx(_components.code, { children: "onClick={() => handleClickInline()}" })] }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 누르기 전" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "7343403" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 7.00 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5560751" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t5.30 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "062" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 5번 누른 후" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "11636043" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t11.09 MB = 4.09 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "9624039" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t9.18 MB = 3.88 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "196" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// = 134 KB 차이" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "고차-함수-onclickhandleclickhighorder", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#고차-함수-onclickhandleclickhighorder", children: _jsx(_components.span, { className: "icon icon-link" }) }), "고차 함수 ", _jsx(_components.code, { children: "onClick={handleClickHighOrder()}" })] }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: "https://prod-files-secure.s3.us-west-2.amazonaws.com/8bf87fbf-5e32-45e1-8f1d-137892d7a2fd/bed4df45-3d94-4a62-b3bb-9d6532c3b754/image.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIAZI2LB466V56HSTJI%2F20250819%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20250819T011023Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEGcaCXVzLXdlc3QtMiJIMEYCIQCYj%2BYN3mSvL4oPV3LZ3u79i8JeBtKjJ4OTILXbIfoIAAIhAIiv6YaiWJOqwezREx24ElGB7BK5AS%2FOOFlBcMeQIwMwKogECLD%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQABoMNjM3NDIzMTgzODA1IgzzkPmmuYKHZPQVz1sq3AOlmqGabYEyWCcFUsnJ0bQV7UgxxdC8tpVwcnSCbT2J3NMSzWb1RtDOcj5ckOF3FmvDepkAQkMYB%2BM0VVZ%2Fwy8RLvcudV%2FH7lxAz5BkV4RDPZzNUe%2Ba3GTGqq0f5fu3lKP5ysuPAFstt2RICozsMA6OiBR67007qd4B%2Bru82QZ4jje3obrC5mOx6lppgr7VzOfuxVWAlzNmRS1KeZ%2FMSTnqOD%2BvEiEaGf0UH7UhD2gkdbg0SyyciAvGFkp8yE33ILyGrzOvWnbdfHwkryODw3loQYKl4m2BLepQ5R4CJEV5DNnsHBR7B9VwjCQSbM3zuwKy3SKSnz6lqPWRb6GBabW7o7gMHP9OHAZurCFqfiRx57Ww2oZL3GOHue3l3lJT8tENJcvxKvpcjcsjKpJddfR04hu1bewIVT2zYkEevqRXV7fWJ5tJDWbmI3xxi0nFz9m4eVY%2Fuuj3wYBDFtqcldp4pQ2UdKoU4XhWrC4nDSy2JL%2BdHFoIHDCQ5FniFQsqeGJ%2FyDQemBedxd6jyOE0Mo3qL%2F9M8ghzgI8nAJ0yhnfFEVOHbgvOJ7BZUGHkF%2BTRQskX4FpaCxuicG6DNGK8ZvsInZyZHBbw0oZJdc83BHoP1X5by37xc1Rwe84QbzCw3I7FBjqkAdt%2FDmKNuFyL3jGmDWw2oDZ%2F%2FiR31fsm4aTeqb8PaALnPaXgj8e%2FviCAdJgcfd9tK4UKP4IZvR6TS9JT3S0Szdl1ICQKNBPVi7o3jRS2S9edrwclUK1CDHxvu3okG53McyDVLIeOL5HZrKGc9jn639Ck0nEsmXny9J9cCllcd1%2Fj42%2FlATera0KEMNk6T2rXl6QitawVU3vfAHqCAlg8fX%2BBGs8g&X-Amz-Signature=897d7e2819895547291bbf230a02883f1e1bc69fb40fc6f29088126eac1e0ea5&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject", alt: "image.png" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 누르기 전" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "7228797" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 6.89 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5775961" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 5.51 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "109" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 5번 누른 후" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "6036679" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 5.76 MB = 1.13 감소" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5067611" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 4.83 MB = 0.68 감소" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "212" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// = 103 KB 차이" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "usecallback-함수-onclickhandleclickusecallback", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#usecallback-함수-onclickhandleclickusecallback", children: _jsx(_components.span, { className: "icon icon-link" }) }), "useCallback 함수 ", _jsx(_components.code, { children: "onClick={handleClickUseCallback}" })] }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: "https://prod-files-secure.s3.us-west-2.amazonaws.com/8bf87fbf-5e32-45e1-8f1d-137892d7a2fd/f9893c45-614b-4ba4-b23f-359570daabc3/image.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIAZI2LB466V56HSTJI%2F20250819%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20250819T011023Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEGcaCXVzLXdlc3QtMiJIMEYCIQCYj%2BYN3mSvL4oPV3LZ3u79i8JeBtKjJ4OTILXbIfoIAAIhAIiv6YaiWJOqwezREx24ElGB7BK5AS%2FOOFlBcMeQIwMwKogECLD%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQABoMNjM3NDIzMTgzODA1IgzzkPmmuYKHZPQVz1sq3AOlmqGabYEyWCcFUsnJ0bQV7UgxxdC8tpVwcnSCbT2J3NMSzWb1RtDOcj5ckOF3FmvDepkAQkMYB%2BM0VVZ%2Fwy8RLvcudV%2FH7lxAz5BkV4RDPZzNUe%2Ba3GTGqq0f5fu3lKP5ysuPAFstt2RICozsMA6OiBR67007qd4B%2Bru82QZ4jje3obrC5mOx6lppgr7VzOfuxVWAlzNmRS1KeZ%2FMSTnqOD%2BvEiEaGf0UH7UhD2gkdbg0SyyciAvGFkp8yE33ILyGrzOvWnbdfHwkryODw3loQYKl4m2BLepQ5R4CJEV5DNnsHBR7B9VwjCQSbM3zuwKy3SKSnz6lqPWRb6GBabW7o7gMHP9OHAZurCFqfiRx57Ww2oZL3GOHue3l3lJT8tENJcvxKvpcjcsjKpJddfR04hu1bewIVT2zYkEevqRXV7fWJ5tJDWbmI3xxi0nFz9m4eVY%2Fuuj3wYBDFtqcldp4pQ2UdKoU4XhWrC4nDSy2JL%2BdHFoIHDCQ5FniFQsqeGJ%2FyDQemBedxd6jyOE0Mo3qL%2F9M8ghzgI8nAJ0yhnfFEVOHbgvOJ7BZUGHkF%2BTRQskX4FpaCxuicG6DNGK8ZvsInZyZHBbw0oZJdc83BHoP1X5by37xc1Rwe84QbzCw3I7FBjqkAdt%2FDmKNuFyL3jGmDWw2oDZ%2F%2FiR31fsm4aTeqb8PaALnPaXgj8e%2FviCAdJgcfd9tK4UKP4IZvR6TS9JT3S0Szdl1ICQKNBPVi7o3jRS2S9edrwclUK1CDHxvu3okG53McyDVLIeOL5HZrKGc9jn639Ck0nEsmXny9J9cCllcd1%2Fj42%2FlATera0KEMNk6T2rXl6QitawVU3vfAHqCAlg8fX%2BBGs8g&X-Amz-Signature=51d5baae52c23ab94a72856dad2e374d86c345ae054b2a195f18371979d4b2b5&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject", alt: "image.png" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 누르기 전" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "6314405" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 6.02 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5581477" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 5.32 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "2" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "941" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 5번 누른 후" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "10312935" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 9.84 MB = 3.82 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "9095279" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t8.67 MB = 3.35 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "033" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// = 92 KB 차이" }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "인라인-익명-함수-onclick", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#인라인-익명-함수-onclick", children: _jsx(_components.span, { className: "icon icon-link" }) }), "인라인 익명 함수 ", _jsx(_components.code, { children: "onClick={()=>{...}}" })] }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.img, { src: 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alt: "image.png" }) }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 누르기 전" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "7377782" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 7.03 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "5876770" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 5.61 MB" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "109" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 5번 누른 후" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "jsHeapSizeLimit" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "4294705152" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "totalJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "11637638" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 11.10 MB = 4.07 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F69D50" }, children: "usedJSHeapSize" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ": " }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "9510450" }), _jsx(_components.span, { style: { color: "#768390" }, children: " // 약 \t9.07 MB = 3.46 증가" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#6CB6FF" }, children: "3" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "," }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: "211" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " KB" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// = 102 KB 차이" }) })] }) }) }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsxs(_components.p, { children: [_jsxs(_components.strong, { children: ["메모리 스냅샷 실험 결과(****", _jsx(_components.code, { children: "Memory Snapshot" })] }), ")"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "인라인 익명 콜백 함수 > 일반 콜백 함수 > 고차 함수 > 인라인 익명 함수 > useCallback 함수" }) }), "\n", _jsxs(_components.p, { children: ["정말 의외의 결과가 나왔다. 내가 주로 사용하는 ", _jsx(_components.code, { children: "()=> handleClick()" }), " 방식이 가장 많은 메모리를 사용한 것이다. 메모리 스냅샷과 메모리를 console로 찍어 확인하는 두가지 방식으로 실험을 거쳤는데, 인라인 익명 함수가 가장 많은 메모리를 사용할 것이라는 예상을 깨고 인라인 콜백 함수가 가장 많은 메모리 사용을 보였다."] }), "\n", _jsx(_components.p, { children: _jsxs(_components.strong, { children: ["메모리 콘솔 실험 결과(", _jsx(_components.strong, { children: _jsx(_components.strong, { children: _jsx(_components.code, { children: "performance.memory" }) }) }), ")"] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "인라인 익명 콜백 함수 > 인라인 익명 함수 > 일반 콜백 함수 > useCallback 함수 > 고차함수" }) }), "\n", _jsx(_components.p, { children: "5번의 클릭을 했을 경우, 대체적으로 3MB~4MB 정도의 메모리 증가를 유발했다. 수치로 환산하니 생각보다 높은 수치이다. 또한, 고차 함수를 실험해보는 도중 전혀 예상과 다른 수치가 나왔는데, 값이 감소한 것이다. GC가 작동했을 가능성이 있는데, 왜 고차 함수에서만 작동을 했을까? 이건 나중에 알아보기로 하자." }), "\n"] }), "\n", _jsxs(_components.h3, { id: "실험에-대한-생각", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#실험에-대한-생각", children: _jsx(_components.span, { className: "icon icon-link" }) }), _jsx(_components.strong, { children: "실험에 대한 생각" })] }), "\n", _jsx(_components.p, { children: "메모리 스냅샷을 찍은 것과 메모리 콘솔로 확인한 결과가 달라서 당황했다. 그러나 콘솔로 찍은 메모리는 실시간으로 돌아가며, 가비지 컬렉터 실행 여부에 따라 값이 달라질 수 있어 정확한 순간을 캐치할 수 없었다. 메모리 스냅샷의 경우, 원하는 순간에 사용되는 메모리를 알아볼 수 있고 할당된 객체와 사용 중인 메모리 크기를 분석한다." }), "\n", _jsx(_components.p, { children: "앞서 추측했듯이 익명 함수가 제일 많은 메모리를 사용할 것이라고 생각했다. 메모리 콘솔에서는 2순위이긴 하지만 스냅샷의 결과에서는 하위권에 속한다. 예측한 결과가 완전히 빗맞은 것이다…" }), "\n", _jsxs(_components.p, { children: ["왜 위와 같은 결과가 나왔는지 생각해보자. GPT에 물어보니 다음과 같은 의견을 얻을 수 있었다. 인라인 익명 콜백 함수, 이름에서 알 수 있듯이 익명 함수가 포함되어 있다. ", _jsx(_components.code, { children: "()=>" }), " 익명 함수이기 때문에 렌더링마다 새로운 함수 객체를 생성한다. 그리고 콜백 함수를 실행하고 내부 로직을 실행한다. 즉, ", _jsx("u", { children: _jsx(_components.strong, { children: "익명 함수 + 콜백 함수" }) }), " ", _jsx("u", { children: "라는 두가지 동작을 하기 때문에 가장 많은 메모리를 사용한 것이다." })] }), "\n", _jsx(_components.p, { children: "그럼, 고차 함수는?? 고차 함수 또한 내부적으로 익명 함수를 사용하지 않나?" }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"click me!\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "<" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "()}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "click" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "!" })] })] }) }) }), "\n", _jsxs(_components.p, { children: ["고차 함수의 구조를 살펴보면, 이벤트에 ", _jsx(_components.code, { children: "handleClick()" }), " 코드를 작성한다. 고차 함수가 아닌 일반 함수라면 즉시 실행될 것이다. 그렇지만, 구조상 고차 함수를 사용해도 외부 함수는 곧바로 실행될 것이다. 그러나 함수를 리턴하고 있어 바로 실행되지 않을 뿐이며, 내부 함수는 렌더링마다 생성된다."] }), "\n", _jsx(_components.p, { children: "이 방식으로 사용했을 때, 익명 콜백 함수보다 메모리 사용이 적은 이유가 곧바로 실행된다는 것이면 어떨까? 즉, 함수 객체를 하나만 생성하는 것으로 익명 콜백 함수보다 적은 메모리를 사용하는 것이다." }), "\n", _jsxs(_components.h3, { id: "익명-함수를-피하고-매개변수를-전달할-방법들", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#익명-함수를-피하고-매개변수를-전달할-방법들", children: _jsx(_components.span, { className: "icon icon-link" }) }), "익명 함수를 피하고 매개변수를 전달할 방법들"] }), "\n", _jsx(_components.p, { children: "어쨌든, 실험 결과만 두고 본다면, 우리는 익명 함수를 꺼려해야 할 이유가 있는 것이다. 익명 함수를 사용하지 않고 어떻게 매개변수를 넘길 수 있을까? 고차 함수 말고 다른 방법은 없을까?" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "useCallback" }), "\n"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " useCallback" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "((" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Clicked item:\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", item);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }, []);" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "<" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{()=> " }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "click" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "!" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 그렇지만, useCallback을 사용해야 할 만큼 메모리 연산이 큰 로직일지에 대한 고려가 필요하다..." }) })] }) }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "고차 함수" }), "\n"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " () " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "\t console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Clicked item:\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", item);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "<" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "handleClick" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ")}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "click" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "!" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 어쨌든 handleClick(item) 호출하게 되면 내부 함수는 익명 함수이지만..." }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 메모리 사용이 적기 때문에 합리적인 사용일 것 같다." }) })] }) }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "bind()" }), "\n"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " handleClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "item" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ") " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "\t console." }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: "log" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"Clicked item:\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", item);" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " " }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "<" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "button onClick" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{handleClick.bind(null, item)}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "click" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "!" })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 괜찮아보이지만, 다른 개발자들로부터 왜 이렇게 했는지 질문을 받게 될 것도 같음..." }) })] }) }) }), "\n", _jsxs(_components.h3, { id: "결론", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#결론", children: _jsx(_components.span, { className: "icon icon-link" }) }), "결론"] }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsxs(_components.p, { children: ["여러가지 방면에서 살펴본 것 같은데, 실험 내역에서 확인할 수 있듯이 함수마다 결과 차이가 크게 나지 않는다. 여기서 그 내용이 떠오르는 것 같다. ", _jsx("u", { children: "성급히 메모리를 최적화하려는 시도 말고, 차라리 코드를 개선하는 시도를 하는 것이 더 나을 수도 있다." })] }), "\n", _jsx(_components.p, { children: "팀에서 요구하는 방식이 있다면, 그걸 따르는 것이 가장 효율적이고, 어쩌면 메모리 낭비를 줄이기 위해 함수 사용을 달리 할 수도 있겠지만, 증명되지 않은 최적화를 가지고 어떻게 설득할 것인지에 대해서도 천천히 생각해봐야 할 문제인 것 같다." }), "\n"] }), "\n", _jsxs(_components.h2, { id: "4️⃣객체오브젝트를-인라인으로-넣는-걸-다시-고려해보세요", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#4️⃣객체오브젝트를-인라인으로-넣는-걸-다시-고려해보세요", children: _jsx(_components.span, { className: "icon icon-link" }) }), "4️⃣ 객체(오브젝트)를 인라인으로 넣는 걸 다시 고려해보세요."] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "javascript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "javascript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// props에 바로 객체를 생성하여 전달" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "Components" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " props" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{name:" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"kim\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "/>" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "ComponentB" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " style" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{ color: " }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"blue\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", background: " }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"gold\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " }" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#768390" }, children: "// 객체를 별도로 저장하여 props로 전달" }) }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " name" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { name:" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"kim\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "};" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " myStyle" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " { color: " }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"blue\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ", background: " }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"gold\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " };" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "Components" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " props" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "name" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "/>" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: "<" }), _jsx(_components.span, { style: { color: "#8DDB8C" }, children: "ComponentB" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " style" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "={" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "myStyle" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "}" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " />" })] })] }) }) }), "\n", _jsx(_components.p, { children: "컴포넌트가 리렌더링 될 때마다 새로운 객체가 생성된다. 특히, props로 객체를 전달하게 되면, 이전 값과 새로운 값을 서로 다른 객체라 판단하기 때문에 불필요한 리렌더링이 발생할 수 있다." }), "\n", _jsx(_components.p, { children: "따라서, 객체를 별도로 저장하고 사용해야 한다. 리렌더링이 되어도 객체는 동일한 메모리 주소를 사용하게 된다. 그렇지만 전역 상태로 유지하는 것에 대한 부작용이 있을 수 있으니 최소한의 범위에서만 사용하는 것이 좋을 듯." }), "\n", _jsxs(_components.h2, { id: "5️⃣reactlazy와-reactsuspense-사용", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#5️⃣reactlazy와-reactsuspense-사용", children: _jsx(_components.span, { className: "icon icon-link" }) }), "5️⃣ ", _jsx(_components.code, { children: "React.lazy" }), "와 ", _jsx(_components.code, { children: "React.Suspense" }), " 사용"] }), "\n", _jsx(_components.figure, { "data-rehype-pretty-code-figure": "", children: _jsx(_components.pre, { style: { backgroundColor: "#22272e", color: "#adbac7" }, tabIndex: "0", "data-language": "typescript", "data-theme": "github-dark-dimmed", children: _jsxs(_components.code, { "data-language": "typescript", "data-theme": "github-dark-dimmed", style: { display: "grid" }, children: [_jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " React, { lazy, Suspense } " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "from" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: " \"react\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ";" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "const" }), _jsx(_components.span, { style: { color: "#6CB6FF" }, children: " BlogPosts" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " =" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " lazy" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(() " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=>" }), _jsx(_components.span, { style: { color: "#F47067" }, children: " import" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "(" }), _jsx(_components.span, { style: { color: "#96D0FF" }, children: "\"./BlogPosts\"" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "));" })] }), "\n", _jsx(_components.span, { "data-line": "", children: " " }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: "function" }), _jsx(_components.span, { style: { color: "#DCBDFB" }, children: " MyBlog" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "() {" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " return" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " (" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#ADBAC7" }, children: " <" }), _jsx(_components.span, { style: { color: "#F69D50" }, children: "div" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: ">" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "Suspense fallback" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "=" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "{

Loading" }), _jsx(_components.span, { style: { color: "#F47067" }, children: "..." }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }), _jsx(_components.span, { style: { color: "#F47067" }, children: ">" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " <" }), _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "BlogPosts " }), _jsx(_components.span, { style: { color: "#F47067" }, children: "/>" })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " " })] }), "\n", _jsxs(_components.span, { "data-line": "", children: [_jsx(_components.span, { style: { color: "#F47067" }, children: " " })] }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: " );" }) }), "\n", _jsx(_components.span, { "data-line": "", children: _jsx(_components.span, { style: { color: "#ADBAC7" }, children: "}" }) })] }) }) }), "\n", _jsx(_components.p, { children: "BlogPosts가 로드될 때까지 화면에는 “로딩중…” 메세지를 표시한다. 비동기 컴포넌트 로드가 완료되면, 그때서야 BlogPosts를 렌더링한다." }), "\n", _jsx(_components.p, { children: "즉, Suspense는 자식 요소를 로드하기 전까지 화면에 대체 UI를 보여준다. 보통은 로딩 스피너나 스켈레톤처럼 간단한 Placeholder를 활용한다. 반대로 fallback을 너무 무겁게 만들면 오히려 렌더링 속도를 느리게 만들 수 있으니 유의해야 한다." }), "\n", _jsx(_components.p, { children: "해당 방법이 메모리 비용을 줄일 수 있는 까닯은 Suspense가 컴포넌트를 메모리에 올리지 않고 렌더링을 지연시키기 때문에 해당 컴포넌트에서 사용되는 state 또한 렌더링하지 않아 메모리 사용량이 줄어든다." }), "\n", _jsxs(_components.p, { children: ["그러나 마찬가지로 너무 작은 컴포넌트까지 ", _jsx(_components.code, { children: "lazy" }), "로 감싸는 것은 의미가 없고, 너무 많은 사용은 잦은 네트워크 요청으로 성능이 저하될 수 있다. ", _jsx(_components.code, { children: "Suspense" }), " 역시, 여러곳에 사용한다면 UI 렌더링이 일관적이지 않다. 따라서 사용하기 전에 정말 이곳에 필요한가에 대한 고민을 해봐야 한다."] }), "\n", _jsxs(_components.h1, { id: "여기까지-학습하고-난-후의-결론", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#여기까지-학습하고-난-후의-결론", children: _jsx(_components.span, { className: "icon icon-link" }) }), "여기까지 학습하고 난 후의 결론"] }), "\n", _jsxs(_components.blockquote, { children: ["\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "익명 함수 > 고차 함수 > 익명 콜백 함수 > 콜백 함수" }) }), "\n"] }), "\n", _jsx(_components.p, { children: "처음 예상에서는 익명 함수가 무조건 메모리 사용이 많을 거라 생각했다. 그러나 직접 실험한 결과는 달랐다. 익명 콜백 함수가 더 많은 메모리를 사용했다. 단순히, 메모리 참조를 통해 같은 함수 객체를 사용한다. 라는 것에만 집중한 나머지, 함수가 실행되는 동작까지는 생각하지 못했던 것이다. 익명 콜백 함수는 두 개의 메모리 공간을 소비하니 한 개의 메모리 공간만 소비하는 익명 함수보다 메모리 사용이 많다." }), "\n", _jsx(_components.p, { children: "또, 가비지 컬렉터가 언제 움직이냐에 따라 메모리 실험 결과도 달라졌는데… 이건 아직 알지 못하는 분야라 가비지 컬렉터가 움직였을 수도 있겠구나 예상만 하고 넘어가야겠다. 혹은 리액트 환경에서 실험을 진행한 것이니 리액트에서 최적화를 실행한 것일 수도 있겠다… 그러나 자세한 내막은 모른다…" }), "\n", _jsx(_components.p, { children: "익명 함수가 메모리를 많이 사용한다는 것에 의문을 가지고 직접 조사하며, 실험까지 한 결과, 한가지 깨달은 것은 있다. 메모리 사용이 겹치면 큰 용량을 차지하겠지만… 이걸 생각만큼 신경써야 할까? 당장 내가 진행하는 프로젝트가 작고 소중한 크기라면 더더욱 신경 쓸 필요는 없겠다. 회사에서 사용하는 대규모 프로젝트라면 어떨까? 고려해볼만 하다. 특히, 성능을 최우선으로 한다면 그렇다." }), "\n", _jsx(_components.p, { children: "함수를 선언하는 것, 성능을 고려하며 작성하는 코드가 팀 내의 규칙으로 존재한다면 그렇게 해도 상관없을 것 같다. 익명 함수를 사용하지 말자. 객체는 따로 선언하여 주입하자. bind를 사용하여 매개변수를 전달한다. 등등… 그렇지만 정해진 것이 없는 코드라면, 성능을 우선시 하는 코드를 작성하는 것과 최적화를 위한 코드 수정이 더 많은 리소스를 잡아먹지 않을까?" }), "\n", _jsx(_components.p, { children: "또, 앞서 작성했듯이 성급한 최적화가 오히려 많은 메모리를 소모할 수도 있다. 타인을 설득하기 위해서는 근거가 필요한 것처럼 최적화에도 근거가 필요하다는 점이다. 성능을 올리고 최적화를 하고 싶다면, 우선 어떤 점이 느린지 증명해야 한다. 이 방법이 빠르다 라는 것보단 이 방법은 느리다를 설명하며, 최적화하는 측면이 더 믿음직스럽지 않을까?" }), "\n", _jsxs(_components.p, { children: ["내가 익명 함수를 조사하며 느낀 바는 위와 같다. 그러나 예상과 다르다는 건 아직도 놀랍다… 진짜로. 고차 함수도 높게 나오긴 했지만 인라인 익명 함수가 더 높게 나온다는 것에… 나는 이렇게 작성해왔는데도. 실질적인 조사도 진행해봤으니 다음부터는 익명 함수 대신 bind나 고차함수를 사용해봐야겠다. ", _jsx(_components.del, { children: "(그러나 리뷰를 하면 왜 사용했는지에 대해서도 매번 설명해야 할 것 같지만…)" })] }), "\n", _jsxs(_components.h1, { id: "참고-자료", children: [_jsx(_components.a, { "aria-hidden": "true", tabIndex: "-1", href: "#참고-자료", children: _jsx(_components.span, { className: "icon icon-link" }) }), "참고 자료"] }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://medium.com/@ryanflorence/react-inline-functions-and-performance-bdff784f5578", children: "https://medium.com/@ryanflorence/react-inline-functions-and-performance-bdff784f5578" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://medium.com/steady-study/%EB%B2%88%EC%97%AD-react-%EC%9D%B8%EB%9D%BC%EC%9D%B8-%ED%95%A8%EC%88%98-%EA%B7%B8%EB%A6%AC%EA%B3%A0-%EC%84%B1%EB%8A%A5-9aef85552f2b", children: "https://medium.com/steady-study/%EB%B2%88%EC%97%AD-react-%EC%9D%B8%EB%9D%BC%EC%9D%B8-%ED%95%A8%EC%88%98-%EA%B7%B8%EB%A6%AC%EA%B3%A0-%EC%84%B1%EB%8A%A5-9aef85552f2b" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://flexport.engineering/ending-the-debate-on-inline-functions-in-react-8c03fabd144", children: "https://flexport.engineering/ending-the-debate-on-inline-functions-in-react-8c03fabd144" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://www.digitalocean.com/community/tutorials/react-keep-react-fast#avoid-anonymous-functions", children: "https://www.digitalocean.com/community/tutorials/react-keep-react-fast#avoid-anonymous-functions" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://www.reddit.com/r/reactjs/comments/uld88i/are_using_anonymous_functions_and_inline/?rdt=55036", children: "https://www.reddit.com/r/reactjs/comments/uld88i/are_using_anonymous_functions_and_inline/?rdt=55036" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://www.reddit.com/r/reactjs/comments/1amtuv3/usememo_or_usecallback_which_should_i_use/", children: "https://www.reddit.com/r/reactjs/comments/1amtuv3/usememo_or_usecallback_which_should_i_use/" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://kentcdodds.com/blog/usememo-and-usecallback", children: "https://kentcdodds.com/blog/usememo-and-usecallback" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://goongoguma.github.io/2021/04/26/When-to-useMemo-and-useCallback/", children: "https://goongoguma.github.io/2021/04/26/When-to-useMemo-and-useCallback/" }) }), "\n", _jsx(_components.p, { children: _jsx(_components.a, { href: "https://dev.to/wallacefreitas/optimizing-re-rendering-in-react-best-practices-5683", children: "https://dev.to/wallacefreitas/optimizing-re-rendering-in-react-best-practices-5683" }) })] }); } function MDXContent(props = {}) { const {wrapper: MDXLayout} = props.components || ({}); return MDXLayout ? _jsx(MDXLayout, { ...props, children: _jsx(_createMdxContent, { ...props }) }) : _createMdxContent(props); } return { default: MDXContent };