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link to 回答关键点" title="Direct link to 回答关键点"></a></h2><p><code>任务队列</code> <code>异步</code> <code>非阻塞</code></p><p>浏览器需要事件循环来协调事件、用户操作、脚本执行、渲染、网络请求等。通过事件循环，浏览器可以利用<strong>任务队列</strong>来管理任务，让异步事件<strong>非阻塞</strong>地执行。每个客户端对应的事件循环是相对独立的。</p><h2 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="知识点深入">知识点深入<a href="#知识点深入" class="hash-link" aria-label="Direct link to 知识点深入" title="Direct link to 知识点深入"></a></h2><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="1-什么是浏览器事件循环">1. 什么是浏览器事件循环<a href="#1-什么是浏览器事件循环" class="hash-link" aria-label="Direct link to 1. 什么是浏览器事件循环" title="Direct link to 1. 什么是浏览器事件循环"></a></h3><blockquote><p>在计算机中，Event Loop 是一个程序结构，用于等待和发送消息和事件。 —— 维基百科</p></blockquote><p>Event Loop 可以理解为一个消息分发器，通过接收和分发不同类型的消息，让执行程序的事件调度更加合理。</p><p><strong>浏览器事件循环是以浏览器为宿主环境实现的事件调度</strong>，操作顺序如下：</p><ol><li>执行同步代码。</li><li>执行一个任务（执行栈中没有就从任务队列中获取）。</li><li>执行过程中如果遇到微任务，就将它添加到微任务的任务队列中。</li><li>任务执行完毕后，立即执行当前微任务队列中的所有微任务（依次执行）。</li><li>当前任务执行完毕，开始检查渲染，然后渲染线程接管进行渲染。</li><li>渲染完毕后，JavaScript 线程继续接管，开始下一个循环。</li></ol><p>下图展示了这个过程：</p><p><img loading="lazy" src="https://user-images.githubusercontent.com/12165373/129468098-f75d76f6-ad01-4390-a155-7fcd179f6a07.gif" alt="browser event loop" class="img_ev3q"></p><blockquote><p>图片来源 <a href="https://www.youtube.com/watch?v=8aGhZQkoFbQ&t=31s" target="_blank" rel="noopener noreferrer">JS CONF EU 2014</a></p></blockquote><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="2-浏览器为什么需要事件循环">2. 浏览器为什么需要事件循环<a href="#2-浏览器为什么需要事件循环" class="hash-link" aria-label="Direct link to 2. 浏览器为什么需要事件循环" title="Direct link to 2. 浏览器为什么需要事件循环"></a></h3><p>由于 JavaScript 是单线程的，且 JavaScript 主线程和渲染线程互斥，如果异步操作（如上图提到的 WebAPIs）阻塞 JavaScript 的执行，会造成浏览器假死。而事件循环为浏览器引入了任务队列（task queue），使得异步任务可以非阻塞地进行。</p><p>一个事件循环有一个或多个任务队列。任务队列是任务的集合，而不是队列。因为事件处理模型会选取<strong>第一个可执行任务</strong>开始执行，而不是队首的任务。</p><p>浏览器事件循环在处理异步任务时不会一直等待其返回结果，而是将这个事件挂起，继续执行栈中的其他任务。当异步事件返回结果，将它放到任务队列中，被放入任务队列不会立刻执行回调，而是等待当前执行栈中所有任务都执行完毕，主线程处于空闲状态，主线程会去查找任务队列中是否有任务，如果有，取出排在第一位的事件，并把这个事件对应的回调放到执行栈中，执行其中的同步代码。</p><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="3-任务与微任务">3. 任务与微任务<a href="#3-任务与微任务" class="hash-link" aria-label="Direct link to 3. 任务与微任务" title="Direct link to 3. 任务与微任务"></a></h3><p>异步任务被分为两类：任务（任务队列中的任务，非微任务）与微任务（microtask），两者的执行优先级也有所区别。</p><p>任务主要包含：script（整体代码）、setTimeout、setInterval、setImmediate、I/O、UI 交互事件。</p><p>微任务主要包含：Promise、MutationObserver 等。微任务队列不属于任务队列。</p><p>在当前执行栈为空的时候，主线程会查看微任务队列是否有事件存在。如果不存在，那么再去任务队列中取出一个事件并把对应的回调加入当前执行栈；如果存在，则会依次执行队列中事件对应的回调，直到微任务队列为空，然后去任务队列中取出最前面的一个事件，把对应的回调加入当前执行栈。如此反复，进入循环。下面通过一个具体的例子来进行分析：</p><div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token known-class-name class-name">Promise</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">resolve</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">then</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// 微任务1</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"Promise1"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token function" style="color:#d73a49">setTimeout</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// 任务2</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"setTimeout2"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">setTimeout</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// 任务1</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"setTimeout1"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token known-class-name class-name">Promise</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">resolve</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">then</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token comment" style="color:#999988;font-style:italic">// 微任务2</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"Promise2"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>最后输出顺序为：<code>Promise1 => setTimeout1 => Promise2 => setTimeout2</code>。具体流程如下：</p><ol><li>同步任务执行完毕。微任务 1 进入微任务队列，任务 1 进入任务队列。</li><li>查看微任务队列，微任务 1 执行，打印 Promise1，生成任务 2，进入任务队列。</li><li>查看任务队列，任务 1 执行，打印 setTimeout1，生成微任务 2，进入微任务队列。</li><li>查看微任务队列，微任务 2 执行，打印 Promise2。</li><li>查看任务队列，任务 2 执行，打印 setTimeout2。</li></ol><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="4-nodejs-中的事件循环">4. Node.js 中的事件循环<a href="#4-nodejs-中的事件循环" class="hash-link" aria-label="Direct link to 4. Node.js 中的事件循环" title="Direct link to 4. Node.js 中的事件循环"></a></h3><p>在 Node.js 中，事件循环表现出的状态与浏览器中大致相同。不同的是 Node.js 中有一套自己的模型。 Node.js 中事件循环的实现是依靠的 libuv 引擎。下图简要介绍了事件循环操作顺序：</p><p><img loading="lazy" src="https://user-images.githubusercontent.com/12165373/129439935-105a2439-23c8-4b2c-aea1-2493c3bf50e9.png" alt="node event loop" class="img_ev3q"></p><blockquote><p>图片来源 <a href="https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#what-is-the-event-loop" target="_blank" rel="noopener noreferrer">Node.js 官网</a></p></blockquote><ol><li>timers：本阶段执行已经被 setTimeout() 和 setInterval() 的调度回调函数。</li><li>pending callbacks：执行延迟到下一个循环迭代的 I/O 回调。</li><li>idle、prepare：仅系统内部使用。</li><li>poll：检索新的 I/O 事件;执行与 I/O 相关的回调（几乎所有情况下，除了关闭的回调函数，那些由计时器和 setImmediate() 调度的之外），其余情况 node 将在适当的时候在此阻塞。</li><li>check：setImmediate() 回调函数在这里执行。</li><li>close callbacks：一些关闭的回调函数，如：socket.on('close', ...)。</li></ol><p>在每次运行的事件循环之间，Node.js 检查它是否在等待任何异步 I/O 或计时器，如果没有的话，则完全关闭。</p><p>需要注意的是，<strong>任务与微任务的执行顺序在 Node.js 的不同版本中表现也有所不同</strong>。同样通过一个具体的例子来分析：</p><div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token function" style="color:#d73a49">setTimeout</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"timer1"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token known-class-name class-name">Promise</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">resolve</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">then</span><span class="token punctuation" style="color:#393A34">(</span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"promise1"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token function" style="color:#d73a49">setTimeout</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token arrow operator" style="color:#393A34">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"timer2"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token known-class-name class-name">Promise</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">resolve</span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">then</span><span class="token punctuation" style="color:#393A34">(</span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">log</span><span class="token punctuation" style="color:#393A34">(</span><span class="token string" style="color:#e3116c">"promise2"</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><ol><li>在 Node.js v11 及以上版本中一旦执行一个阶段里的一个任务（setTimeout，setInterval 和 setImmediate），会立刻执行微任务队列，所以输出顺序为<code>timer1 => promise1 => timer2 => promise2</code>。</li><li>在 Node.js v10 及以下版本，要看第一个定时器执行完成时，第二个定时器是否在完成队列中。<ul><li>如果第二个定时器还未在完成队列中，输出顺序为<code>timer1 => promise1 => timer2 => promise2</code>。</li><li>如果是第二个定时器已经在完成队列中，输出顺序为<code>timer1 => timer2 => promise1 => promise2</code>。</li></ul></li></ol><h2 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="参考资料">参考资料<a href="#参考资料" class="hash-link" aria-label="Direct link to 参考资料" title="Direct link to 参考资料"></a></h2><ol><li><a href="https://html.spec.whatwg.org/multipage/webappapis.html#event-loops" target="_blank" rel="noopener noreferrer">whatwg event loops</a></li><li><a href="https://en.wikipedia.org/wiki/Event_loop" target="_blank" rel="noopener noreferrer">wikipedia event loops</a></li><li><a href="https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#what-is-the-event-loop" target="_blank" rel="noopener noreferrer">Node.js event loops</a></li></ol></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages navigation"><a class="pagination-nav__link pagination-nav__link--prev" href="/awesome-interview/book2/topic-multi-pics-site-optimize"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">综合：多图站点性能优化</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/awesome-interview/book3/browser-memory-leaks"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">浏览器：如何定位内存泄露</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#相关问题" class="table-of-contents__link toc-highlight">相关问题</a></li><li><a href="#回答关键点" class="table-of-contents__link toc-highlight">回答关键点</a></li><li><a href="#知识点深入" class="table-of-contents__link toc-highlight">知识点深入</a><ul><li><a href="#1-什么是浏览器事件循环" class="table-of-contents__link toc-highlight">1. 什么是浏览器事件循环</a></li><li><a href="#2-浏览器为什么需要事件循环" class="table-of-contents__link toc-highlight">2. 浏览器为什么需要事件循环</a></li><li><a href="#3-任务与微任务" class="table-of-contents__link toc-highlight">3. 任务与微任务</a></li><li><a href="#4-nodejs-中的事件循环" class="table-of-contents__link toc-highlight">4. Node.js 中的事件循环</a></li></ul></li><li><a href="#参考资料" class="table-of-contents__link toc-highlight">参考资料</a></li></ul></div></div></div><div class="row"><div class="col"><div class="react-utterences"><div>Loading script...</div></div></div><div class="col col--3"></div></div></div></main></div></div></div>
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