{"id":486,"date":"2023-09-26T19:50:23","date_gmt":"2023-09-26T11:50:23","guid":{"rendered":"https:\/\/www.escook.cn\/?p=486"},"modified":"2023-09-26T21:02:35","modified_gmt":"2023-09-26T13:02:35","slug":"react-hooks-useeffect-uselayouteffect","status":"publish","type":"post","link":"https:\/\/www.escook.cn\/index.php\/2023\/09\/26\/react-hooks-useeffect-uselayouteffect\/","title":{"rendered":"React Hooks &#8211; useEffect &#038; useLayoutEffect"},"content":{"rendered":"<blockquote>\n<p>\u7248\u6743\u5f52\u4f5c\u8005 <strong>\u00a9\u5218\u9f99\u5bbe<\/strong> \u6240\u6709\uff0c\u672c\u6587\u7ae0\u672a\u7ecf\u4f5c\u8005\u5141\u8bb8\uff0c\u7981\u6b62\u79c1\u81ea\u8f6c\u8f7d\uff01<\/p>\n<\/blockquote>\n<h2>1. useEffect<\/h2>\n<h3>\u4ec0\u4e48\u662f\u51fd\u6570\u7684\u526f\u4f5c\u7528<\/h3>\n<p>\u51fd\u6570\u7684\u526f\u4f5c\u7528\u5c31\u662f\u51fd\u6570<strong>\u9664\u4e86\u8fd4\u56de\u503c\u5916<\/strong>\u5bf9<strong>\u5916\u754c\u73af\u5883<\/strong>\u9020\u6210\u7684<strong>\u5176\u5b83\u5f71\u54cd<\/strong>\uff0c\u5373\u4e0e\u7ec4\u4ef6\u6e32\u67d3\u65e0\u5173\u7684\u64cd\u4f5c\u3002\u4f8b\u5982<strong>\u83b7\u53d6\u6570\u636e<\/strong>\u3001<strong>\u4fee\u6539\u5168\u5c40\u53d8\u91cf<\/strong>\u3001<strong>\u66f4\u65b0 DOM<\/strong> \u7b49\u3002<\/p>\n<p>useEffect \u662f React \u4e2d\u7684 hooks API\u3002\u901a\u8fc7 useEffect \u53ef\u4ee5\u6267\u884c\u4e00\u4e9b\u526f\u4f5c\u7528\u64cd\u4f5c\uff0c\u4f8b\u5982\uff1a\u8bf7\u6c42\u6570\u636e\u3001\u4e8b\u4ef6\u76d1\u542c\u7b49\u3002\u5b83\u7684\u8bed\u6cd5\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-js\">useEffect(fn, deps?)<\/code><\/pre>\n<p>\u5176\u4e2d\uff0c<\/p>\n<ul>\n<li>\u7b2c\u4e00\u4e2a\u53c2\u6570 <strong>fn<\/strong> \u662f\u4e00\u4e2a\u526f\u4f5c\u7528\u51fd\u6570\uff0c\u8be5\u51fd\u6570\u4f1a\u5728<strong>\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u4e4b\u540e<\/strong>\u88ab\u8c03\u7528\u3002<\/li>\n<li>\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f<strong>\u53ef\u9009\u7684\u4f9d\u8d56\u9879\u6570\u7ec4<\/strong>\uff0c\u8fd9\u4e2a\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e00\u9879\u5185\u5bb9\u90fd\u4f1a\u88ab\u7528\u6765\u8fdb\u884c<strong>\u6e32\u67d3\u524d\u540e\u7684\u5bf9\u6bd4<\/strong>\u3002\n<ul>\n<li>\u5f53\u4f9d\u8d56\u9879\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u4f1a\u91cd\u65b0\u6267\u884c fn \u526f\u4f5c\u7528\u51fd\u6570<\/li>\n<li>\u5f53\u4f9d\u8d56\u9879\u6ca1\u6709\u4efb\u4f55\u53d8\u5316\u65f6\uff0c\u5219\u4e0d\u4f1a\u6267\u884c fn \u526f\u4f5c\u7528\u51fd\u6570<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h3>useEffect \u7684\u6267\u884c\u65f6\u673a<\/h3>\n<p>\u5982\u679c\u6ca1\u6709\u4e3a useEffect \u6307\u5b9a\u4f9d\u8d56\u9879\u6570\u7ec4\uff0c\u5219 Effect \u4e2d\u7684\u526f\u4f5c\u7528\u51fd\u6570\uff0c\u4f1a\u5728\u51fd\u6570\u7ec4\u4ef6<strong>\u6bcf\u6b21<\/strong>\u6e32\u67d3<strong>\u5b8c\u6210\u540e<\/strong>\u6267\u884c\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u5728\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u57fa\u4e8e useEffect \u83b7\u53d6 h1 \u5143\u7d20\u6700\u65b0\u7684 innerText\uff1a<\/p>\n<pre><code class=\"language-tsx\">import React, { useEffect, useState } from &#039;react&#039;\n\nexport const Counter: React.FC = () =&gt; {\n  const [count, setCount] = useState(0)\n\n  \/\/ \u6ce8\u610f\uff1a\u8fd9\u91cc\u6bcf\u6b21\u8f93\u51fa\u7684\u90fd\u662f\u4e0a\u4e00\u6b21\u7684\u65e7\u503c\n  \/\/ console.log(document.querySelector(&#039;h1&#039;)?.innerHTML)\n\n  const add = () =&gt; {\n    setCount((prev) =&gt; prev + 1)\n  }\n\n  \/\/ \u5728\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u4e4b\u540e\uff0c\u90fd\u4f1a\u91cd\u65b0\u6267\u884c effect \u4e2d\u7684\u56de\u8c03\u51fd\u6570\n  useEffect(() =&gt; {\n    console.log(document.querySelector(&#039;h1&#039;)?.innerHTML)\n  })\n\n  return (\n    &lt;&gt;\n      &lt;h1&gt;count \u503c\u4e3a\uff1a{count}&lt;\/h1&gt;\n      &lt;button onClick={add}&gt;+1&lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<h3>deps \u4e3a\u7a7a\u6570\u7ec4<\/h3>\n<p>\u5982\u679c\u4e3a useEffect \u6307\u5b9a\u4e86\u4e00\u4e2a\u7a7a\u6570\u7ec4 <code>[]<\/code> \u4f5c\u4e3a deps \u4f9d\u8d56\u9879\uff0c\u5219\u526f\u4f5c\u7528\u51fd\u6570\u53ea\u4f1a\u5728\u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\u6267\u884c\u552f\u4e00\u7684\u4e00\u6b21\u3002\u5f53\u7ec4\u4ef6 rerender \u7684\u65f6\u5019\u4e0d\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002\u4f8b\u5982\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0cuseEffect \u4e2d\u7684 console.log() \u53ea\u4f1a\u6267\u884c1\u6b21\uff1a<\/p>\n<pre><code class=\"language-jsx\">import React, { useEffect, useState } from &#039;react&#039;\n\nexport const Counter: React.FC = () =&gt; {\n  const [count, setCount] = useState(0)\n\n  const add = () =&gt; {\n    setCount((prev) =&gt; prev + 1)\n  }\n\n  \/\/ \u4ec5\u5728\u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\uff0c\u4f1a\u6267\u884c effect \u4e2d\u7684\u56de\u8c03\u51fd\u6570\n  useEffect(() =&gt; {\n    console.log(document.querySelector(&#039;h1&#039;)?.innerHTML)\n  }, [])\n\n  return (\n    &lt;&gt;\n      &lt;h1&gt;count \u503c\u4e3a\uff1a{count}&lt;\/h1&gt;\n      &lt;button onClick={add}&gt;+1&lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<h3>deps \u4e3a\u4f9d\u8d56\u9879\u6570\u7ec4<\/h3>\n<p>\u5982\u679c\u60f3<strong>\u6709\u6761\u4ef6\u5730<\/strong>\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684<strong>\u91cd\u65b0\u6267\u884c<\/strong>\uff0c\u5219\u9700\u8981\u901a\u8fc7 deps \u6570\u7ec4\u6307\u5b9a<strong>\u4f9d\u8d56\u9879\u5217\u8868<\/strong>\u3002<\/p>\n<p>React \u4f1a\u5728\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\uff0c\u5bf9\u6bd4\u6e32\u67d3\u524d\u540e\u7684\u6bcf\u4e00\u4e2a\u4f9d\u8d56\u9879\u662f\u5426\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u53ea\u8981\u4efb\u4f55\u4e00\u4e2a\u4f9d\u8d56\u9879\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u90fd\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002\u5426\u5219\uff0c\u5982\u679c\u6240\u6709\u4f9d\u8d56\u9879\u5728\u6e32\u67d3\u524d\u540e\u90fd\u6ca1\u6709\u53d1\u751f\u53d8\u5316\uff0c\u5219\u4e0d\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002<\/p>\n<p>\u4e0b\u9762\u7684\u4f8b\u5b50\u6f14\u793a\u4e86\u4f9d\u8d56\u9879\u7684\u4f7f\u7528\uff1a\u53ea\u6709\u5f53 count \u503c\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u624d\u4f1a\u89e6\u53d1 effect \u56de\u8c03\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\uff0cflag \u503c\u7684\u53d8\u5316\u4e0d\u4f1a\u89e6\u53d1\uff1a<\/p>\n<pre><code class=\"language-jsx\">import React, { useEffect, useState } from &#039;react&#039;\n\nexport const Counter: React.FC = () =&gt; {\n  const [count, setCount] = useState(0)\n  const [flag, setFlag] = useState(false)\n\n  const add = () =&gt; {\n    setCount((prev) =&gt; prev + 1)\n  }\n\n  \/\/ \u5728\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\uff0c\u5982\u679c count \u503c\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u5219\u6267\u884c effect \u4e2d\u7684\u56de\u8c03\n  \/\/ \u5176\u5b83\u72b6\u6001\u7684\u53d8\u5316\uff0c\u4e0d\u4f1a\u5bfc\u81f4\u6b64\u56de\u8c03\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\n  useEffect(() =&gt; {\n    console.log(document.querySelector(&#039;h1&#039;)?.innerHTML)\n  }, [count])\n\n  return (\n    &lt;&gt;\n      &lt;h1&gt;count \u503c\u4e3a\uff1a{count}&lt;\/h1&gt;\n      &lt;p&gt;flag \u7684\u503c\u4e3a\uff1a{String(flag)}&lt;\/p&gt;\n      &lt;button onClick={add}&gt;+1&lt;\/button&gt;\n      &lt;button onClick={() =&gt; setFlag((prev) =&gt; !prev)}&gt;Toggle&lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<blockquote>\n<p>\u6ce8\u610f\uff1a<strong>\u4e0d\u5efa\u8bae<\/strong>\u628a<strong>\u5bf9\u8c61<\/strong>\u4f5c\u4e3a useEffect \u7684<strong>\u4f9d\u8d56\u9879<\/strong>\uff0c\u56e0\u4e3a React \u4f7f\u7528 <a href=\"https:\/\/developer.mozilla.org\/zh-CN\/docs\/Web\/JavaScript\/Reference\/Global_Objects\/Object\/is\">Object.is()<\/a> \u6765\u5224\u65ad\u4f9d\u8d56\u9879\u662f\u5426\u53d1\u751f\u53d8\u5316\u3002<\/p>\n<\/blockquote>\n<h3>\u5982\u4f55\u6e05\u7406\u526f\u4f5c\u7528<\/h3>\n<p>useEffect \u53ef\u4ee5\u8fd4\u56de\u4e00\u4e2a\u51fd\u6570\uff0c\u7528\u4e8e\u6e05\u9664\u526f\u4f5c\u7528\u7684\u56de\u8c03\u3002\u8bed\u6cd5\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-jsx\">useEffect(() =&gt; {\n  \/\/ 1. \u6267\u884c\u526f\u4f5c\u7528\u64cd\u4f5c\n  \/\/ 2. \u8fd4\u56de\u4e00\u4e2a\u6e05\u7406\u526f\u4f5c\u7528\u7684\u51fd\u6570\n  return () =&gt; { \/* \u5728\u8fd9\u91cc\u6267\u884c\u81ea\u5df1\u7684\u6e05\u7406\u64cd\u4f5c *\/ }\n}, [\u4f9d\u8d56\u9879])<\/code><\/pre>\n<blockquote>\n<p>\u5b9e\u9645\u5e94\u7528\u573a\u666f\uff1a\u5982\u679c\u5f53\u524d\u7ec4\u4ef6\u4e2d\u4f7f\u7528\u4e86<strong>\u5b9a\u65f6\u5668<\/strong>\u6216\u7ed1\u5b9a\u4e86<strong>\u4e8b\u4ef6\u76d1\u542c\u7a0b\u5e8f<\/strong>\uff0c\u53ef\u4ee5\u5728\u8fd4\u56de\u7684\u51fd\u6570\u4e2d\u6e05\u9664\u5b9a\u65f6\u5668\u6216\u89e3\u7ed1\u76d1\u542c\u7a0b\u5e8f\u3002<\/p>\n<\/blockquote>\n<h3>\u7ec4\u4ef6\u5378\u8f7d\u65f6\u7ec8\u6b62\u672a\u5b8c\u6210\u7684 Ajax \u8bf7\u6c42<\/h3>\n<p>\u5728\u7236\u7ec4\u4ef6 <code>TestRandomColor<\/code> \u4e2d\uff0c\u4f7f\u7528\u5e03\u5c14\u503c flag \u63a7\u5236\u5b50\u7ec4\u4ef6 <code>RandomColor<\/code> \u7684\u5c55\u793a\u4e0e\u9690\u85cf\uff1a<\/p>\n<pre><code class=\"language-jsx\">export const TestRandomColor: React.FC = () =&gt; {\n  const [flag, setFlag] = useState(true)\n\n  return (\n    &lt;&gt;\n      &lt;button onClick={() =&gt; setFlag((prev) =&gt; !prev)}&gt;Toggle&lt;\/button&gt;\n      &lt;hr \/&gt;\n      {flag &amp;&amp; &lt;RandomColor \/&gt;}\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u5728\u5b50\u7ec4\u4ef6 <code>RandomColor<\/code> \u4e2d\uff0c\u901a\u8fc7 <code>useEffect(fn, [])<\/code> \u58f0\u660e\u4e00\u4e2a\u526f\u4f5c\u7528\u51fd\u6570\uff0c\u8be5\u526f\u4f5c\u7528\u51fd\u6570\u4ec5\u5728\u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6bd5\u540e\u6267\u884c\u3002\u5728\u8be5\u526f\u4f5c\u7528\u51fd\u6570\u4e2d\uff0c\u57fa\u4e8e fetch API \u8bf7\u6c42\u6570\u636e\uff0c\u5e76\u4e14\u5728\u6e05\u7406\u51fd\u6570\u4e2d\u4f7f\u7528 <code>AbortController<\/code> \u5bf9\u8c61\u81ea\u52a8\u7ec8\u6b62\u672a\u5b8c\u6210\u7684 Ajax \u8bf7\u6c42\u3002\u793a\u4f8b\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-jsx\">const RandomColor: React.FC = () =&gt; {\n  const [color, setColor] = useState(&#039;&#039;)\n\n  useEffect(() =&gt; {\n    const controller = new AbortController()\n\n    fetch(&#039;https:\/\/api.liulongbin.top\/v1\/color&#039;, { signal: controller.signal })\n      .then((res) =&gt; res.json())\n      .then((res) =&gt; {\n        console.log(res)\n        setColor(res.data.color)\n      })\n      .catch((err) =&gt; console.log(&#039;\u6d88\u606f\uff1a&#039; + err.message))\n\n    \/\/ return \u6e05\u7406\u51fd\u6570\n    \/\/ \u6e05\u7406\u51fd\u6570\u89e6\u53d1\u7684\u65f6\u673a\u6709\u4e24\u4e2a\uff1a\n    \/\/ 1. \u7ec4\u4ef6\u88ab\u5378\u8f7d\u7684\u65f6\u5019\uff0c\u4f1a\u8c03\u7528\n    \/\/ 2. \u5f53 effect \u526f\u4f5c\u7528\u51fd\u6570\u88ab\u518d\u6b21\u6267\u884c\u4e4b\u524d\uff0c\u4f1a\u5148\u6267\u884c\u6e05\u7406\u51fd\u6570\n    return () =&gt; controller.abort()\n  }, [])\n\n  return (\n    &lt;&gt;\n      &lt;p&gt;color \u7684\u989c\u8272\u503c\u662f\uff1a{color}&lt;\/p&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<h3>\u83b7\u53d6\u9f20\u6807\u5728\u7f51\u9875\u4e2d\u79fb\u52a8\u65f6\u7684\u4f4d\u7f6e<\/h3>\n<p>\u793a\u4f8b\u4ee3\u7801\u5982\u4e0b\uff0c\u5148\u58f0\u660e\u4e00\u4e2a <strong>MouseInfo<\/strong> \u7684\u5b50\u7ec4\u4ef6\uff0c\u7528\u6765\u76d1\u542c\u9f20\u6807\u7684\u79fb\u52a8\u5e76\u6253\u5370\u9f20\u6807\u7684\u4f4d\u7f6e\uff1a<\/p>\n<pre><code class=\"language-jsx\">const MouseInfo: React.FC = () =&gt; {\n  \/\/ \u8bb0\u5f55\u9f20\u6807\u7684\u4f4d\u7f6e\n  const [position, setPosition] = useState({ x: 0, y: 0 })\n\n  \/\/ \u526f\u4f5c\u7528\u51fd\u6570\n  useEffect(() =&gt; {\n    \/\/ 1. \u8981\u7ed1\u5b9a\u6216\u89e3\u7ed1\u7684 mousemove \u4e8b\u4ef6\u5904\u7406\u51fd\u6570\n    const mouseMoveHandler = (e: MouseEvent) =&gt; {\n      console.log({ x: e.clientX, y: e.clientY })\n      setPosition({ x: e.clientX, y: e.clientY })\n    }\n\n    \/\/ 2. \u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6bd5\u540e\uff0c\u4e3a window \u5bf9\u8c61\u7ed1\u5b9a mousemove \u4e8b\u4ef6\n    window.addEventListener(&#039;mousemove&#039;, mouseMoveHandler)\n\n    \/\/ 3. \u8fd4\u56de\u4e00\u4e2a\u6e05\u7406\u7684\u51fd\u6570\uff0c\u5728\u6bcf\u6b21\u7ec4\u4ef6\u5378\u8f7d\u65f6\uff0c\u4e3a window \u5bf9\u8c61\u89e3\u7ed1 mousemove \u4e8b\u4ef6\n    return () =&gt; window.removeEventListener(&#039;mousemove&#039;, mouseMoveHandler)\n  }, [])\n\n  return (\n    &lt;&gt;\n      &lt;p&gt;\u9f20\u6807\u7684\u4f4d\u7f6e\uff1a{JSON.stringify(position)}&lt;\/p&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u518d\u58f0\u660e\u4e00\u4e2a <strong>TestMouseInfo<\/strong> \u7684\u7236\u7ec4\u4ef6\uff0c\u901a\u8fc7\u5e03\u5c14\u503c flag \u63a7\u5236\u5b50\u7ec4\u4ef6 <strong>MouseInfo<\/strong> \u7684\u663e\u793a\u6216\u9690\u85cf\uff1a<\/p>\n<pre><code class=\"language-jsx\">export const TestMouseInfo: React.FC = () =&gt; {\n  \/\/ \u5b9a\u4e49\u5e03\u5c14\u503c flag\uff0c\u63a7\u5236\u5b50\u7ec4\u4ef6\u7684\u663e\u793a\u6216\u9690\u85cf\n  const [flag, setFlag] = useState(true)\n\n  return (\n    &lt;&gt;\n      &lt;h3&gt;\u7236\u7ec4\u4ef6&lt;\/h3&gt;\n      {\/* \u70b9\u51fb\u6309\u94ae\uff0c\u5207\u6362 flag \u7684\u503c *\/}\n      &lt;button onClick={() =&gt; setFlag((prev) =&gt; !prev)}&gt;Toggle&lt;\/button&gt;\n      &lt;hr \/&gt;\n      {flag &amp;&amp; &lt;MouseInfo \/&gt;}\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<h3>\u81ea\u5b9a\u4e49\u5c01\u88c5\u9f20\u6807\u4f4d\u7f6e\u7684 hook<\/h3>\n<p>\u5728 <code>src<\/code> \u76ee\u5f55\u4e0b\u65b0\u5efa <code>hooks\/index.ts<\/code> \u6a21\u5757\uff0c\u5e76\u628a\u521a\u624d\u83b7\u53d6\u9f20\u6807\u4f4d\u7f6e\u7684\u4ee3\u7801\u5c01\u88c5\u6210\u540d\u4e3a <code>useMousePosition<\/code> \u7684\u81ea\u5b9a\u4e49 hook\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-js\">import { useState, useEffect } from &#039;react&#039;\n\nexport const useMousePosition = () =&gt; {\n  \/\/ \u8bb0\u5f55\u9f20\u6807\u7684\u4f4d\u7f6e\n  const [position, setPosition] = useState({ x: 0, y: 0 })\n\n  \/\/ \u526f\u4f5c\u7528\u51fd\u6570\n  useEffect(() =&gt; {\n    \/\/ 1. \u8981\u7ed1\u5b9a\u6216\u89e3\u7ed1\u7684 mousemove \u4e8b\u4ef6\u5904\u7406\u51fd\u6570\n    const mouseMoveHandler = (e: MouseEvent) =&gt; {\n      setPosition({ x: e.clientX, y: e.clientY })\n    }\n\n    \/\/ 2. \u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6bd5\u540e\uff0c\u4e3a window \u5bf9\u8c61\u7ed1\u5b9a mousemove \u4e8b\u4ef6\n    window.addEventListener(&#039;mousemove&#039;, mouseMoveHandler)\n\n    \/\/ 3. \u8fd4\u56de\u4e00\u4e2a\u6e05\u7406\u7684\u51fd\u6570\uff0c\u5728\u6bcf\u6b21\u7ec4\u4ef6\u5378\u8f7d\u65f6\uff0c\u4e3a window \u5bf9\u8c61\u89e3\u7ed1 mousemove \u4e8b\u4ef6\n    return () =&gt; window.removeEventListener(&#039;mousemove&#039;, mouseMoveHandler)\n  }, [])\n\n  return position\n}<\/code><\/pre>\n<p>\u5728 <strong>MouseInfo<\/strong> \u7ec4\u4ef6\u4e2d\uff0c\u53ef\u4ee5\u5bfc\u5165\u81ea\u5df1\u5c01\u88c5\u7684 hook \u8fdb\u884c\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"language-jsx\">import { useMousePosition } from &#039;@\/hooks\/index.ts&#039;\n\nconst MouseInfo: React.FC = () =&gt; {\n  \/\/ \u8c03\u7528\u81ea\u5b9a\u4e49\u7684 hook\uff0c\u83b7\u53d6\u9f20\u6807\u7684\u4f4d\u7f6e\u4fe1\u606f\n  const position = useMousePosition()\n\n  return (\n    &lt;&gt;\n      &lt;!-- \u8f93\u51fa\u9f20\u6807\u7684\u4f4d\u7f6e\u4fe1\u606f --&gt;\n      &lt;p&gt;\u9f20\u6807\u7684\u4f4d\u7f6e\uff1a{JSON.stringify(position)}&lt;\/p&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u5728 TestMouseInfo \u7ec4\u4ef6\u4e2d\uff0c\u4e5f\u53ef\u4ee5\u5bfc\u5165\u81ea\u5df1\u5c01\u88c5\u7684 hook \u8fdb\u884c\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"language-jsx\">import { useMousePosition } from &#039;@\/hooks\/index.ts&#039;\n\nexport const TestMouseInfo: React.FC = () =&gt; {\n  const [flag, setFlag] = useState(true)\n  \/\/ \u8c03\u7528\u81ea\u5b9a\u4e49\u7684 hook\uff0c\u83b7\u53d6\u9f20\u6807\u7684\u4f4d\u7f6e\u4fe1\u606f\n  const position = useMousePosition()\n\n  return (\n    &lt;&gt;\n      &lt;!-- \u8f93\u51fa\u9f20\u6807\u7684\u4f4d\u7f6e\u4fe1\u606f --&gt;\n      &lt;h3&gt;\u7236\u7ec4\u4ef6 {position.x + position.y}&lt;\/h3&gt;\n      &lt;button onClick={() =&gt; setFlag((prev) =&gt; !prev)}&gt;Toggle&lt;\/button&gt;\n      &lt;hr \/&gt;\n      {flag &amp;&amp; &lt;MouseInfo \/&gt;}\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<h3>\u81ea\u5b9a\u4e49\u5c01\u88c5\u79d2\u6570\u5012\u8ba1\u65f6\u7684 hook<\/h3>\n<p>\u529f\u80fd\u5206\u6790\uff1a<\/p>\n<ol>\n<li>\u7528\u6237\u8c03\u7528 <code>useCountDown(5)<\/code> \u7684 hook\uff0c\u53ef\u4ee5\u4f20\u9012\u5012\u8ba1\u65f6\u7684\u79d2\u6570\uff0c\u5982\u679c\u672a\u6307\u5b9a\u79d2\u6570\u5219\u9ed8\u8ba4\u503c\u4e3a 10 \u79d2<\/li>\n<li>\u5728 <code>useCountDown<\/code> \u4e2d\uff0c\u9700\u8981\u5bf9\u7528\u6237\u4f20\u9012\u8fdb\u884c\u6765\u7684\u6570\u5b57\u8fdb\u884c\u975e\u6cd5\u503c\u7684\u5224\u65ad\u548c\u5904\u7406\uff08\u5904\u7406\u8d1f\u6570\u3001\u5c0f\u6570\u30010\uff09<\/li>\n<li>\u6bcf\u96941\u79d2\u8ba9\u79d2\u6570 <code>-1<\/code>\uff0c\u5e76\u4f7f\u7528\u4e00\u4e2a\u5e03\u5c14\u503c\u8bb0\u5f55\u6309\u94ae\u662f\u5426\u88ab\u7981\u7528<\/li>\n<li>\u4ee5\u6570\u7ec4\u7684\u5f62\u5f0f\uff0c\u5411\u5916\u8fd4\u56de\u6bcf\u6b21\u7684\u79d2\u6570\u548c\u5f53\u524d\u7684\u7981\u7528\u72b6\u6001\uff0c\u4f8b\u5982 <code>return [count, disabled]<\/code><\/li>\n<\/ol>\n<p>\u6700\u7ec8\uff0c\u7528\u6237\u53ef\u4ee5\u6309\u7167\u5982\u4e0b\u7684\u65b9\u5f0f\uff0c\u4f7f\u7528\u6211\u4eec\u5c01\u88c5\u7684 <code>useCountDown<\/code> hook\uff1a<\/p>\n<pre><code class=\"language-jsx\">import React from &#039;react&#039;\n\/\/ 1. \u5bfc\u5165\u81ea\u5b9a\u4e49\u7684 hook\nimport { useCountDown } from &#039;@\/hooks\/index.ts&#039;\n\nexport const CountDown: React.FC = () =&gt; {\n  \/\/ 2. \u8c03\u7528\u81ea\u5b9a\u4e49\u7684 hook\n  const [count, disabled] = useCountDown(3)\n\n  return (\n    &lt;&gt;\n      &lt;!-- 3. \u5c55\u793a\u5012\u8ba1\u65f6\u7684\u79d2\u6570\uff0c\u5e76\u63a7\u5236\u6309\u94ae\u7684\u7981\u7528\u72b6\u6001 --&gt;\n      &lt;button disabled={disabled} onClick={() =&gt; console.log(&#039;\u534f\u8bae\u751f\u6548\uff01&#039;)}&gt;\n        {disabled ? `\u8bf7\u4ed4\u7ec6\u9605\u8bfb\u672c\u534f\u8bae\u5185\u5bb9\uff08${count} \u79d2\uff09` : &#039;\u786e\u8ba4\u6b64\u534f\u8bae&#039;}\n      &lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u63a5\u4e0b\u6765\uff0c\u6211\u4eec\u53ef\u4ee5\u5728 <code>src\/hooks\/index.ts<\/code> \u6a21\u5757\u4e2d\uff0c\u5c01\u88c5\u540d\u4e3a <code>useCountDown<\/code> \u7684\u81ea\u5b9a\u4e49 hook\u3002\u5177\u4f53\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-js\">import { useState, useEffect } from &#039;react&#039;\n\n\/\/ TS \u7c7b\u578b\ntype UseCountDown = (seconds: number) =&gt; [number, boolean]\n\nexport const useCountDown: UseCountDown = (seconds = 10) =&gt; {\n  \/\/ \u5bf9\u5916\u754c\u4f20\u9012\u7684\u6570\u503c\u8fdb\u884c\u975e\u6cd5\u503c\u5904\u7406\uff1a\n  \/\/ 1. \u5148\u6c42\u7edd\u5bf9\u503c\n  \/\/ 2. \u518d\u5bf9\u5c0f\u6570\u8fdb\u884c\u56db\u820d\u4e94\u5165\n  \/\/ 3. \u5982\u679c\u5904\u7406\u7684\u7ed3\u679c\u4e3a\u6570\u5b57 0\uff0c\u5219\u5c06\u9ed8\u8ba4\u503c\u8bbe\u4e3a 10\n  seconds = Math.round(Math.abs(seconds)) || 10\n\n  \/\/ \u8ba1\u6570\u5668\n  const [count, setCount] = useState(seconds)\n  \/\/ \u5012\u8ba1\u65f6\u662f\u5426\u7ed3\u675f disabled \u4e3a false \u8868\u793a\u7ed3\u675f\uff0c\u4e3a true \u8868\u793a\u672a\u7ed3\u675f\n  const [disabled, setDisabled] = useState(true)\n\n  useEffect(() =&gt; {\n    const timerId = setTimeout(() =&gt; {\n      if (count &gt; 1) {\n        setCount((prev) =&gt; prev - 1)\n      } else {\n        setDisabled(false)\n      }\n    }, 1000)\n\n    \/\/ \u8fd4\u56de\u6e05\u7406\u51fd\u6570\uff0c\u518d\u6b21\u6267\u884c useEffect \u7684\u526f\u4f5c\u7528\u51fd\u6570\u4e4b\u524d\uff0c\u5148\u8fd0\u884c\u4e0a\u6b21 return \u7684\u6e05\u7406\u51fd\u6570\n    return () =&gt; clearTimeout(timerId)\n  }, [count])\n\n  \/\/ \u8fd4\u56de count \u548c disabled \u4f9b\u7ec4\u4ef6\u4f7f\u7528\n  \/\/ 1. count \u7528\u6765\u663e\u793a\u5012\u8ba1\u65f6\u7684\u79d2\u6570\n  \/\/ 2. disabled \u7528\u6765\u63a7\u5236\u6309\u94ae\u662f\u5426\u7981\u7528 Or \u5012\u8ba1\u65f6\u662f\u5426\u7ed3\u675f\n  return [count, disabled]\n}<\/code><\/pre>\n<h3>useEffect \u7684\u4f7f\u7528\u6ce8\u610f\u4e8b\u9879<\/h3>\n<ol>\n<li>\u4e0d\u8981\u5728 useEffect \u4e2d\u6539\u53d8\u4f9d\u8d56\u9879\u7684\u503c\uff0c\u4f1a\u9020\u6210\u6b7b\u5faa\u73af\u3002<\/li>\n<li>\u591a\u4e2a\u4e0d\u540c\u529f\u80fd\u7684\u526f\u4f5c\u7528\u5c3d\u91cf\u5206\u5f00\u58f0\u660e\uff0c\u4e0d\u8981\u5199\u5230\u4e00\u4e2a useEffect \u4e2d\u3002<\/li>\n<\/ol>\n<h2>2. useLayoutEffect<\/h2>\n<h3>useLayoutEffect \u548c useEffect \u7684\u5bf9\u6bd4<\/h3>\n<h4>1. \u7528\u6cd5\u76f8\u4f3c<\/h4>\n<p>useLayoutEffect \u548c useEffect \u7684\u4f7f\u7528\u65b9\u5f0f\u5f88\u76f8\u4f3c\uff1a<\/p>\n<ol>\n<li>useLayout \u63a5\u6536\u4e00\u4e2a\u51fd\u6570\u548c\u4e00\u4e2a\u4f9d\u8d56\u9879\u6570\u7ec4\u4f5c\u4e3a\u53c2\u6570<\/li>\n<li>\u53ea\u6709\u5728\u6570\u7ec4\u4e2d\u7684\u4f9d\u8d56\u9879\u53d1\u751f\u6539\u53d8\u65f6\u624d\u4f1a\u518d\u6b21\u6267\u884c\u526f\u4f5c\u7528\u51fd\u6570<\/li>\n<li>useLayoutEffect \u4e5f\u53ef\u4ee5\u8fd4\u56de\u4e00\u4e2a\u6e05\u7406\u51fd\u6570<\/li>\n<\/ol>\n<h4>2. \u533a\u522b<\/h4>\n<table>\n<thead>\n<tr>\n<th>hooks \u540d\u79f0<\/th>\n<th>\u6267\u884c\u65f6\u673a<\/th>\n<th>\u6267\u884c\u8fc7\u7a0b<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>useEffect<\/td>\n<td>\u5728\u6d4f\u89c8\u5668\u91cd\u65b0\u7ed8\u5236\u5c4f\u5e55<strong>\u4e4b\u540e<\/strong>\u89e6\u53d1<\/td>\n<td>\u5f02\u6b65\u6267\u884c\uff0c\u4e0d\u963b\u585e\u6d4f\u89c8\u5668\u7ed8\u5236<\/td>\n<\/tr>\n<tr>\n<td>useLayoutEffect<\/td>\n<td>\u5728\u6d4f\u89c8\u5668\u91cd\u65b0\u7ed8\u5236\u5c4f\u5e55<strong>\u4e4b\u524d<\/strong>\u89e6\u53d1<\/td>\n<td>\u540c\u6b65\u6267\u884c\uff0c\u963b\u585e\u6d4f\u89c8\u5668\u91cd\u65b0\u7ed8\u5236<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<blockquote>\n<p>\u6ce8\u610f\uff1aReact \u4fdd\u8bc1\u4e86 <code>useLayoutEffect<\/code> \u4e2d\u7684\u4ee3\u7801\u4ee5\u53ca\u5176\u4e2d\u4efb\u4f55\u8ba1\u5212\u7684\u72b6\u6001\u66f4\u65b0\u90fd\u4f1a\u5728\u6d4f\u89c8\u5668\u91cd\u65b0\u7ed8\u5236\u5c4f\u5e55\u4e4b\u524d\u5f97\u5230\u5904\u7406\u3002<\/p>\n<\/blockquote>\n<h4>3. \u4ee3\u7801\u793a\u4f8b<\/h4>\n<p>\u70b9\u51fb\u6309\u94ae\uff0c\u628a num \u503c\u8bbe\u7f6e\u4e3a 0\uff0c\u5f53\u9875\u9762\u66f4\u65b0\u5b8c\u6210\u540e\uff0c\u5224\u65ad num \u662f\u5426\u7b49\u4e8e 0\uff0c\u5982\u679c\u7b49\u4e8e 0\uff0c\u5219\u5728 useEffect \u4e2d\u628a num \u8d4b\u503c\u4e3a\u968f\u673a\u7684\u6570\u5b57\uff1a<\/p>\n<pre><code class=\"language-jsx\">export const RandomNumber: React.FC = () =&gt; {\n  const [num, setNum] = useState(Math.random() * 200)\n\n  useEffect(() =&gt; {\n    if (num === 0) {\n      setNum(10 + Math.random() * 200)\n    }\n  }, [num])\n\n  return (\n    &lt;&gt;\n      &lt;h1&gt;num \u7684\u503c\u662f\uff1a{num}&lt;\/h1&gt;\n      &lt;button onClick={() =&gt; setNum(0)}&gt;\u91cd\u7f6e num&lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u8fd0\u884c\u4e0a\u9762\u7684\u4ee3\u7801\uff0c\u6211\u4eec\u4f1a\u53d1\u73b0\u8fd9\u4e32\u6570\u5b57\u4f1a\u51fa\u73b0\u95ea\u70c1\u7684\u60c5\u51b5\u3002\u539f\u56e0\u662f\u9875\u9762\u4f1a\u5148\u5c06 h1 \u6e32\u67d3\u4e3a 0\uff0c\u7136\u540e\u518d\u6e32\u67d3\u6210\u968f\u673a\u7684\u6570\u5b57\uff0c\u7531\u4e8e\u66f4\u65b0\u7684\u5f88\u5feb\u4fbf\u51fa\u73b0\u4e86\u95ea\u70c1\u3002<\/p>\n<p>\u4e3a\u4e86\u89e3\u51b3\u4e0a\u8ff0\u95ee\u9898\uff0c\u53ef\u4ee5\u628a useEffect \u66ff\u6362\u4e3a useLayoutEffect\uff1a<\/p>\n<pre><code class=\"language-jsx\">export const RandomNumber: React.FC = () =&gt; {\n  const [num, setNum] = useState(Math.random() * 200)\n\n  useLayoutEffect(() =&gt; {\n    if (num === 0) {\n      setNum(10 + Math.random() * 200)\n    }\n  }, [num])\n\n  return (\n    &lt;&gt;\n      &lt;h1&gt;num \u7684\u503c\u662f\uff1a{num}&lt;\/h1&gt;\n      &lt;button onClick={() =&gt; setNum(0)}&gt;\u91cd\u7f6e num&lt;\/button&gt;\n    &lt;\/&gt;\n  )\n}<\/code><\/pre>\n<p>\u66f4\u6539\u5b8c\u6210\u540e\u518d\u6b21\u8fd0\u884c\u4ee3\u7801\uff0c\u53d1\u73b0\u6570\u5b57\u4e0d\u518d\u95ea\u70c1\u4e86\u3002\u56e0\u4e3a\u70b9\u51fb\u6309\u94ae\u65f6\uff0cnum \u66f4\u65b0\u4e3a 0\uff0c\u4f46\u6b64\u65f6\u9875\u9762\u4e0d\u4f1a\u6e32\u67d3\uff0c\u800c\u662f\u7b49\u5f85 useLayoutEffect \u5185\u90e8\u72b6\u6001\u4fee\u6539\u540e\u624d\u4f1a\u66f4\u65b0\u9875\u9762\uff0c\u6240\u4ee5\u4e0d\u4f1a\u51fa\u73b0\u95ea\u70c1\u3002<\/p>\n<blockquote>\n<p>\u7248\u6743\u5f52\u4f5c\u8005 <strong>\u00a9\u5218\u9f99\u5bbe<\/strong> \u6240\u6709\uff0c\u672c\u6587\u7ae0\u672a\u7ecf\u4f5c\u8005\u5141\u8bb8\uff0c\u7981\u6b62\u79c1\u81ea\u8f6c\u8f7d\uff01<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>\u7248\u6743\u5f52\u4f5c\u8005 \u00a9\u5218\u9f99\u5bbe \u6240\u6709\uff0c\u672c\u6587\u7ae0\u672a\u7ecf\u4f5c\u8005\u5141\u8bb8\uff0c\u7981\u6b62\u79c1\u81ea\u8f6c\u8f7d\uff01 1. useEffect \u4ec0\u4e48\u662f\u51fd\u6570\u7684\u526f\u4f5c\u7528 \u51fd\u6570\u7684\u526f\u4f5c\u7528\u5c31\u662f\u51fd\u6570\u9664\u4e86\u8fd4\u56de\u503c\u5916\u5bf9\u5916\u754c\u73af\u5883\u9020\u6210\u7684\u5176\u5b83\u5f71\u54cd\uff0c\u5373\u4e0e\u7ec4\u4ef6\u6e32\u67d3\u65e0\u5173\u7684\u64cd\u4f5c\u3002\u4f8b\u5982\u83b7\u53d6\u6570\u636e\u3001\u4fee\u6539\u5168\u5c40\u53d8\u91cf\u3001\u66f4\u65b0 DOM \u7b49\u3002 useEffect \u662f React \u4e2d\u7684 hooks API\u3002\u901a\u8fc7 useEffect \u53ef\u4ee5\u6267\u884c\u4e00\u4e9b\u526f\u4f5c\u7528\u64cd\u4f5c\uff0c\u4f8b\u5982\uff1a\u8bf7\u6c42\u6570\u636e\u3001\u4e8b\u4ef6\u76d1\u542c\u7b49\u3002\u5b83\u7684\u8bed\u6cd5\u683c\u5f0f\u5982\u4e0b\uff1a useEffect(fn, deps?) \u5176\u4e2d\uff0c \u7b2c\u4e00\u4e2a\u53c2\u6570 fn \u662f\u4e00\u4e2a\u526f\u4f5c\u7528\u51fd\u6570\uff0c\u8be5\u51fd\u6570\u4f1a\u5728\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u4e4b\u540e\u88ab\u8c03\u7528\u3002 \u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u53ef\u9009\u7684\u4f9d\u8d56\u9879\u6570\u7ec4\uff0c\u8fd9\u4e2a\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e00\u9879\u5185\u5bb9\u90fd\u4f1a\u88ab\u7528\u6765\u8fdb\u884c\u6e32\u67d3\u524d\u540e\u7684\u5bf9\u6bd4\u3002 \u5f53\u4f9d\u8d56\u9879\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u4f1a\u91cd\u65b0\u6267\u884c fn \u526f\u4f5c\u7528\u51fd\u6570 \u5f53\u4f9d\u8d56\u9879\u6ca1\u6709\u4efb\u4f55\u53d8\u5316\u65f6\uff0c\u5219\u4e0d\u4f1a\u6267\u884c fn \u526f\u4f5c\u7528\u51fd\u6570 useEffect \u7684\u6267\u884c\u65f6\u673a \u5982\u679c\u6ca1\u6709\u4e3a useEffect \u6307\u5b9a\u4f9d\u8d56\u9879\u6570\u7ec4\uff0c\u5219 Effect \u4e2d\u7684\u526f\u4f5c\u7528\u51fd\u6570\uff0c\u4f1a\u5728\u51fd\u6570\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\u6267\u884c\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u5728\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0c\u57fa\u4e8e useEffect \u83b7\u53d6 h1 \u5143\u7d20\u6700\u65b0\u7684 innerText\uff1a import React, { useEffect, useState } from &#039;react&#039; export const Counter: React.FC = () =&gt; { const [count, setCount] = useState(0) \/\/ \u6ce8\u610f\uff1a\u8fd9\u91cc\u6bcf\u6b21\u8f93\u51fa\u7684\u90fd\u662f\u4e0a\u4e00\u6b21\u7684\u65e7\u503c \/\/ console.log(document.querySelector(&#039;h1&#039;)?.innerHTML) const add = () =&gt; { setCount((prev) =&gt; prev + 1) } \/\/ \u5728\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u4e4b\u540e\uff0c\u90fd\u4f1a\u91cd\u65b0\u6267\u884c effect \u4e2d\u7684\u56de\u8c03\u51fd\u6570 useEffect(() =&gt; { console.log(document.querySelector(&#039;h1&#039;)?.innerHTML) }) return ( &lt;&gt; &lt;h1&gt;count \u503c\u4e3a\uff1a{count}&lt;\/h1&gt; &lt;button onClick={add}&gt;+1&lt;\/button&gt; &lt;\/&gt; ) } deps \u4e3a\u7a7a\u6570\u7ec4 \u5982\u679c\u4e3a useEffect \u6307\u5b9a\u4e86\u4e00\u4e2a\u7a7a\u6570\u7ec4 [] \u4f5c\u4e3a deps \u4f9d\u8d56\u9879\uff0c\u5219\u526f\u4f5c\u7528\u51fd\u6570\u53ea\u4f1a\u5728\u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\u6267\u884c\u552f\u4e00\u7684\u4e00\u6b21\u3002\u5f53\u7ec4\u4ef6 rerender \u7684\u65f6\u5019\u4e0d\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002\u4f8b\u5982\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0cuseEffect \u4e2d\u7684 console.log() \u53ea\u4f1a\u6267\u884c1\u6b21\uff1a import React, { useEffect, useState } from &#039;react&#039; export const Counter: React.FC = () =&gt; { const [count, setCount] = useState(0) const add = () =&gt; { setCount((prev) =&gt; prev + 1) } \/\/ \u4ec5\u5728\u7ec4\u4ef6\u9996\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\uff0c\u4f1a\u6267\u884c effect \u4e2d\u7684\u56de\u8c03\u51fd\u6570 useEffect(() =&gt; { console.log(document.querySelector(&#039;h1&#039;)?.innerHTML) }, []) return ( &lt;&gt; &lt;h1&gt;count \u503c\u4e3a\uff1a{count}&lt;\/h1&gt; &lt;button onClick={add}&gt;+1&lt;\/button&gt; &lt;\/&gt; ) } deps \u4e3a\u4f9d\u8d56\u9879\u6570\u7ec4 \u5982\u679c\u60f3\u6709\u6761\u4ef6\u5730\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\uff0c\u5219\u9700\u8981\u901a\u8fc7 deps \u6570\u7ec4\u6307\u5b9a\u4f9d\u8d56\u9879\u5217\u8868\u3002 React \u4f1a\u5728\u7ec4\u4ef6\u6bcf\u6b21\u6e32\u67d3\u5b8c\u6210\u540e\uff0c\u5bf9\u6bd4\u6e32\u67d3\u524d\u540e\u7684\u6bcf\u4e00\u4e2a\u4f9d\u8d56\u9879\u662f\u5426\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u53ea\u8981\u4efb\u4f55\u4e00\u4e2a\u4f9d\u8d56\u9879\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u90fd\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002\u5426\u5219\uff0c\u5982\u679c\u6240\u6709\u4f9d\u8d56\u9879\u5728\u6e32\u67d3\u524d\u540e\u90fd\u6ca1\u6709\u53d1\u751f\u53d8\u5316\uff0c\u5219\u4e0d\u4f1a\u89e6\u53d1\u526f\u4f5c\u7528\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\u3002 \u4e0b\u9762\u7684\u4f8b\u5b50\u6f14\u793a\u4e86\u4f9d\u8d56\u9879\u7684\u4f7f\u7528\uff1a\u53ea\u6709\u5f53 count \u503c\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u624d\u4f1a\u89e6\u53d1 effect \u56de\u8c03\u51fd\u6570\u7684\u91cd\u65b0\u6267\u884c\uff0cflag \u503c\u7684\u53d8\u5316\u4e0d\u4f1a\u89e6\u53d1\uff1a import React, { useEffect, useState } from &#039;react&#039; export const Counter: React.FC = () =&gt; { const [count, setCount] = useState(0) const [flag, setFlag] = useState&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16,15],"tags":[18,17,20,19],"class_list":["post-486","post","type-post","status-publish","format-standard","hentry","category-hooks","category-react","tag-hooks","tag-react","tag-react-hook","tag-react-hooks"],"_links":{"self":[{"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/posts\/486","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/comments?post=486"}],"version-history":[{"count":14,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/posts\/486\/revisions"}],"predecessor-version":[{"id":572,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/posts\/486\/revisions\/572"}],"wp:attachment":[{"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/media?parent=486"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/categories?post=486"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.escook.cn\/index.php\/wp-json\/wp\/v2\/tags?post=486"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}