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Deploy website - based on 46f351e1ba99c3cc2e917e36e9066a0be0953120
2021-09-05 17:06:43 +08:00
<!doctype html>
<html lang="en" dir="ltr">
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<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="generator" content="Docusaurus v2.0.0-beta.5">
Deploy website - based on 0daf2bb5b2120d892d9d716982ee279e94f07fe0
2021-09-18 23:50:59 +08:00
<link rel="search" type="application/opensearchdescription+xml" title="HZFE - 剑指前端 Offer" href="/awesome-interview/opensearch.xml">
Deploy website - based on 6785bba05ee5b1fba643c168c956d7551678c3a8
2021-09-14 00:38:16 +08:00
<link rel="preconnect" href="https://hm.baidu.com">
Deploy website - based on 4078649f75a4d60851ddff34aa00f7cddc3e23ea
2021-10-14 23:08:15 +08:00
<script>var _hmt=_hmt||[];!function(){var e=document.createElement("script");e.src="https://hm.baidu.com/hm.js?c7cd0fd77ac518cc6ef46461cdc9524b";var c=document.getElementsByTagName("script")[0];c.parentNode.insertBefore(e,c)}()</script><title data-react-helmet="true">常见框架的 Diff 算法 | HZFE - 剑指前端 Offer</title><meta data-react-helmet="true" name="twitter:card" content="summary_large_image"><meta data-react-helmet="true" property="og:url" content="https://febook.hzfe.org/awesome-interview/book3/frame-diff"><meta data-react-helmet="true" name="docsearch:language" content="en"><meta data-react-helmet="true" name="docsearch:version" content="current"><meta data-react-helmet="true" name="docsearch:docusaurus_tag" content="docs-default-current"><meta data-react-helmet="true" property="og:title" content="常见框架的 Diff 算法 | HZFE - 剑指前端 Offer"><meta data-react-helmet="true" name="description" content="相关问题"><meta data-react-helmet="true" property="og:description" content="相关问题"><link data-react-helmet="true" rel="shortcut icon" href="/awesome-interview/img/favicon.ico"><link data-react-helmet="true" rel="canonical" href="https://febook.hzfe.org/awesome-interview/book3/frame-diff"><link data-react-helmet="true" rel="alternate" href="https://febook.hzfe.org/awesome-interview/book3/frame-diff" hreflang="en"><link data-react-helmet="true" rel="alternate" href="https://febook.hzfe.org/awesome-interview/book3/frame-diff" hreflang="x-default"><link data-react-helmet="true" rel="preconnect" href="https://BH4D9OD16A-dsn.algolia.net" crossorigin="anonymous"><link rel="stylesheet" href="/awesome-interview/assets/css/styles.304d13b7.css">
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Deploy website - based on 46f351e1ba99c3cc2e917e36e9066a0be0953120
2021-09-05 17:06:43 +08:00
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<script>!function(){function t(t){document.documentElement.setAttribute("data-theme",t)}var e=function(){var t=null;try{t=localStorage.getItem("theme")}catch(t){}return t}();t(null!==e?e:"light")}()</script><div id="__docusaurus">
Deploy website - based on 0daf2bb5b2120d892d9d716982ee279e94f07fe0
2021-09-18 23:50:59 +08:00
<div><a href="#" class="skipToContent_1oUP">Skip to main content</a></div><nav class="navbar navbar--fixed-top navbarHideable_2qcr"><div class="navbar__inner"><div class="navbar__items"><button aria-label="Navigation bar toggle" class="navbar__toggle clean-btn" type="button" tabindex="0"><svg width="30" height="30" viewBox="0 0 30 30" aria-hidden="true"><path stroke="currentColor" stroke-linecap="round" stroke-miterlimit="10" stroke-width="2" d="M4 7h22M4 15h22M4 23h22"></path></svg></button><a class="navbar__brand" href="/awesome-interview/"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_1VuW themedImage--light_3UqQ navbar__logo"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_1VuW themedImage--dark_hz6m navbar__logo"><b class="navbar__title">剑指前端 Offer</b></a></div><div class="navbar__items navbar__items--right"><a href="https://github.com/hzfe/awesome-interview" target="_blank" rel="noopener noreferrer" class="navbar__item navbar__link"><span>GitHub<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_3J9K"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></span></a><div class="searchBox_1Doo"><button type="button" class="DocSearch DocSearch-Button" aria-label="Search"><span class="DocSearch-Button-Container"><svg width="20" height="20" class="DocSearch-Search-Icon" viewBox="0 0 20 20"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.9418 2.9419-7.7115 2.9419-10.6533 0-2.9419-2.9418-2.9419-7.7115 0-10.6533 2.9418-2.9419 7.7115-2.9419 10.6533 0 2.9419 2.9418 2.9419 7.7115 0 10.6533z" stroke="currentColor" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round"></path></svg><span class="DocSearch-Button-Placeholder">Search</span></span><span class="DocSearch-Button-Keys"></span></button></div></div></div><div role="presentation" class="navbar-sidebar__backdrop"></div></nav><div class="main-wrapper docs-wrapper docs-doc-page"><div class="docPage_31aa"><button class="clean-btn backToTopButton_35hR" type="button"><svg viewBox="0 0 24 24" width="28"><path d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z" fill="currentColor"></path></svg></button><aside class="docSidebarContainer_3Kbt"><div class="sidebar_15mo sidebarWithHideableNavbar_267A"><a tabindex="-1" class="sidebarLogo_3h0W" href="/awesome-interview/"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_1VuW themedImage--light_3UqQ"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_1VuW themedImage--dark_hz6m"><b>剑指前端 Offer</b></a><nav class="menu thin-scrollbar menu_Bmed menuWithAnnouncementBar_2WvA"><ul class="menu__list"><li class="menu__list-item"><a class="menu__link" href="/awesome-interview/about">关于我们</a></li><li class="menu__list-item"><a class="menu__link" href="/awesome-interview/">前言</a></li><li class="menu__list-item menu__list-item--collapsed"><a class="menu__link menu__link--sublist" href="#">模拟题一</a></li><li class="menu__list-item menu__list-item--collapsed"><a class="menu__link menu__link--sublist" href="#">模拟题二</a></li><li class="menu__list-item"><a class="menu__link menu__link--sublist menu__link--active" href="#">模拟题三</a><ul style="display:block;overflow:visible;height:auto" class="menu__list"><li class="menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book3/browser-event-loop">浏览器：浏览器事件循环</a></li><li class="menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book3/browser-memory-leaks">浏览器：如何定位内存泄露</a></li><li class="menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book3/engineer-webpack-loader">工程化：谈下 webpack loader 的机制</a></li><li class="menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book3/frame-react-hooks">框架：React Hooks 实现原理</a></li><l
Deploy website - based on 46f351e1ba99c3cc2e917e36e9066a0be0953120
2021-09-05 17:06:43 +08:00
</span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- new --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">div</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">class</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">bg-blue-100</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">div</span><span class="token tag punctuation" style="color:#393A34">&gt;</span></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_Ue-o clean-btn">Copy</button></div></div></li><li><p><strong>相同类型的元素</strong></p><p>如果元素是两个相同类型的 React DOM 元素时，React 会查看两者的属性，保留 DOM 节点，只更新改变的属性。如以下情况，React 只更新颜色样式。</p><div class="codeBlockContainer_K1bP"><div class="codeBlockContent_hGly html"><pre tabindex="0" class="prism-code language-html codeBlock_23N8 thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_39YC"><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- old --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">button</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">class</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">bg-blue-100 text-center</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">button</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block">
</span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- new --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">button</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">class</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">bg-red-100 text-center</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">button</span><span class="token tag punctuation" style="color:#393A34">&gt;</span></span></code></pre><button type="button" aria-label="Copy code to clipboard" class="copyButton_Ue-o clean-btn">Copy</button></div></div></li></ol><p>在元素类型相同的情况下，比对完元素后，会递归元素的子元素。默认情况下，React 会同时迭代新老两个子元素列表。对于列表的更新，React 建议在列表项中标识 key 属性。避免以下低效场景：</p><div class="codeBlockContainer_K1bP"><div class="codeBlockContent_hGly html"><pre tabindex="0" class="prism-code language-html codeBlock_23N8 thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_39YC"><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- bad --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- React 不会意识到可以保留&lt;li&gt;HZFE&lt;/li&gt;和&lt;li&gt;Front-End&lt;/li&gt;子树的完整，而是重写每个元素 --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block">
</span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- old --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">Front-End</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- new --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">Back-End</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">Front-End</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class
</span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- good --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- 子列表项有稳定且在兄弟节点中唯一的 key 属性， --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- React 使用 key 从新老树中匹配对应节点比较，提高 Diff 效率。 --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block">
Deploy website - based on 0daf2bb5b2120d892d9d716982ee279e94f07fe0
2021-09-18 23:50:59 +08:00
</span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- old --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">key</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">2016</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">HZFE</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">key</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">2017</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain">Front-End</span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">li</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;/</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">&lt;!-- new --&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">ul</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token plain"></span></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#393A34">&lt;</span><span class="token tag" style="color:#00009f">li</span><span class="token tag" style="color:#00009f"> </span><span class="token tag attr-name" style="color:#00a4db">key</span><span class="token tag attr-value punctuation attr-equals" style="color:#393A34">=</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag attr-value" style="color:#e3116c">2015</span><span class="token tag attr-value punctuation" style="color:#393A34">&quot;</span><span class="token tag punctuation" style="color:#393A34">&gt;</span><span class="token p
Deploy website - based on 4078649f75a4d60851ddff34aa00f7cddc3e23ea
2021-10-14 23:08:15 +08:00
<script src="/awesome-interview/assets/js/runtime~main.e4536af0.js"></script>
<script src="/awesome-interview/assets/js/main.52f9823f.js"></script>
Deploy website - based on 46f351e1ba99c3cc2e917e36e9066a0be0953120
2021-09-05 17:06:43 +08:00
</body>
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