{"id":53067,"date":"2024-12-03T13:05:31","date_gmt":"2024-12-03T05:05:31","guid":{"rendered":"https:\/\/fwq.ai\/blog\/53067\/"},"modified":"2024-12-03T13:05:31","modified_gmt":"2024-12-03T05:05:31","slug":"%e4%ba%86%e8%a7%a3-react-%e7%9a%84-usememo%ef%bc%9a%e5%ae%83%e7%9a%84%e4%bd%9c%e7%94%a8%e3%80%81%e4%bd%95%e6%97%b6%e4%bd%bf%e7%94%a8%e5%ae%83%e4%bb%a5%e5%8f%8a%e6%9c%80%e4%bd%b3%e5%ae%9e%e8%b7%b5","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/53067\/","title":{"rendered":"\u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5"},"content":{"rendered":"

<\/b> <\/p>\n

\u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5<\/h1>\n

<\/i>\u6536\u85cf<\/span> <\/p>\n

\u6700\u8fd1\u53d1\u73b0\u4e0d\u5c11\u5c0f\u4f19\u4f34\u90fd\u5bf9\u6587\u7ae0<\/span>\u5f88\u611f\u5174\u8da3\uff0c\u6240\u4ee5\u4eca\u5929\u7ee7\u7eed\u7ed9\u5927\u5bb6\u4ecb\u7ecd\u6587\u7ae0<\/span>\u76f8\u5173\u7684\u77e5\u8bc6\uff0c\u672c\u6587\u300a\u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5\u300b<\/span>\u4e3b\u8981\u5185\u5bb9\u6d89\u53ca\u5230<\/span>\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u80fd\u5e2e\u5230\u4f60\uff01\u5f53\u7136\u5982\u679c\u9605\u8bfb\u672c\u6587\u65f6\u5b58\u5728\u4e0d\u540c\u60f3\u6cd5\uff0c\u53ef\u4ee5\u5728\u8bc4\u8bba\u4e2d\u8868\u8fbe\uff0c\u4f46\u662f\u8bf7\u52ff\u4f7f\u7528\u8fc7\u6fc0\u7684\u63aa\u8f9e~<\/p>\n

\"\u4e86\u89e3<\/p>\n

react \u662f\u4e00\u4e2a\u7528\u4e8e\u6784\u5efa\u7528\u6237\u754c\u9762\u7684\u5f3a\u5927\u5e93\uff0c\u4f46\u968f\u7740\u5e94\u7528\u7a0b\u5e8f\u7684\u589e\u957f\uff0c\u60a8\u53ef\u80fd\u4f1a\u6ce8\u610f\u5230\u6027\u80fd\u6709\u65f6\u4f1a\u6210\u4e3a\u95ee\u9898\u3002\u8fd9\u5c31\u662f\u50cf usememo \u8fd9\u6837\u7684 react hook \u53d1\u6325\u4f5c\u7528\u7684\u5730\u65b9\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u6df1\u5165\u63a2\u8ba8 usememo \u7684\u4f5c\u7528\u3001\u4f55\u65f6\u6709\u7528\u4ee5\u53ca\u4f7f\u7528\u5b83\u7684\u6700\u4f73\u5b9e\u8df5\u3002\u6211\u4eec\u8fd8\u5c06\u4ecb\u7ecd\u4e00\u4e9b\u9700\u8981\u907f\u514d\u7684\u5e38\u89c1\u9677\u9631\u3002<\/p>\n

\u4ec0\u4e48\u662f usememo\uff1f <\/h2>\n

usememo \u662f\u4e00\u4e2a react hook\uff0c\u5141\u8bb8\u4f60\u8bb0\u4f4f\u8ba1\u7b97\u7ed3\u679c\u3002\u7b80\u5355\u6765\u8bf4\uff0c\u5b83\u4f1a\u8bb0\u4f4f\u51fd\u6570\u7684\u7ed3\u679c\uff0c\u5e76\u4e14\u4ec5\u5728\u5176\u4f9d\u8d56\u9879\u53d1\u751f\u53d8\u5316\u65f6\u624d\u91cd\u65b0\u8ba1\u7b97\u5b83\u3002\u8fd9\u53ef\u4ee5\u9632\u6b62\u4e0d\u5fc5\u8981\u7684\u8ba1\u7b97\u5e76\u63d0\u9ad8\u6027\u80fd\u3002<\/p>\n

\u8fd9\u662f\u4e00\u4e2a\u57fa\u672c\u793a\u4f8b\uff1a<\/p>\n

import react, { usememo } from 'react';\n\nfunction expensivecalculation({ num }) {\n  const result = usememo(() => {\n    console.log('calculating...');\n    return num * 2;\n  }, [num]);\n\n  return <div>the result is {result}<\/div>;\n}\n\n<\/pre>\n
\u5728\u6b64\u793a\u4f8b\u4e2d\uff0cusememo \u4e2d\u7684\u51fd\u6570\u4ec5\u5728 num \u66f4\u6539\u65f6\u8fd0\u884c\u3002\u5982\u679c num \u4fdd\u6301\u4e0d\u53d8\uff0creact \u5c06\u8df3\u8fc7\u8ba1\u7b97\u5e76\u4f7f\u7528\u4e4b\u524d\u5b58\u50a8\u7684\u7ed3\u679c\u3002<\/p>\n
 \u4e3a\u4ec0\u4e48\u4f7f\u7528 usememo\uff1f <\/h2>\n
\u4f7f\u7528 usememo \u7684\u4e3b\u8981\u539f\u56e0\u662f\u4f18\u5316\u6027\u80fd\u3002\u5728 react \u4e2d\uff0c\u53ea\u8981\u7ec4\u4ef6\u7684\u72b6\u6001\u6216 props \u53d1\u751f\u53d8\u5316\uff0c\u7ec4\u4ef6\u5c31\u4f1a\u91cd\u65b0\u6e32\u67d3\u3002\u8fd9\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6602\u8d35\u7684\u8ba1\u7b97\u8fd0\u884c\u9891\u7387\u8d85\u8fc7\u5fc5\u8981\u7684\u9891\u7387\uff0c\u7279\u522b\u662f\u5728\u8ba1\u7b97\u5f88\u590d\u6742\u6216\u7ec4\u4ef6\u6811\u5f88\u5927\u7684\u60c5\u51b5\u4e0b\u3002<\/p>\n
 \u4ee5\u4e0b\u662f usememo \u7279\u522b\u6709\u7528\u7684\u4e00\u4e9b\u573a\u666f\uff1a <\/h2>\n
 1. \u6602\u8d35\u7684\u8ba1\u7b97\uff1a <\/h2>\n
\u5047\u8bbe\u60a8\u6709\u4e00\u4e2a\u6267\u884c\u7e41\u91cd\u8ba1\u7b97\u7684\u7ec4\u4ef6\uff0c\u4f8b\u5982\u8fc7\u6ee4\u5927\u578b\u6570\u636e\u96c6\u3002\u5982\u679c\u6ca1\u6709 usememo\uff0c\u6b64\u8ba1\u7b97\u5c06\u5728\u6bcf\u6b21\u6e32\u67d3\u4e0a\u8fd0\u884c\uff0c\u8fd9\u53ef\u80fd\u4f1a\u51cf\u6162\u60a8\u7684\u5e94\u7528\u7a0b\u5e8f\u7684\u901f\u5ea6\u3002<\/p>\n
import react, { usememo } from 'react';\n\nfunction expensivecalculationcomponent({ numbers }) {\n  \/\/ expensive calculation: filtering even numbers\n  const evennumbers = usememo(() => {\n    console.log('filtering even numbers...');\n    return numbers.filter(num => num % 2 === 0);\n  }, [numbers]);\n\n  return (\n    <div>\n      <h2>even numbers<\/h2>\n      <ul>\n        {evennumbers.map((num) => (\n          <li key={num}>{num}<\/li>\n        ))}\n      <\/ul>\n    <\/div>\n  );\n}\n\n\/\/ usage\nconst numbersarray = array.from({ length: 100000 }, (_, i) => i + 1);\nexport default function app() {\n  return <expensivecalculationcomponent numbers={numbersarray} \/>;\n}\n<\/pre>\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u8fc7\u6ee4\u64cd\u4f5c\u7684\u8ba1\u7b97\u91cf\u5f88\u5927\u3002\u901a\u8fc7\u5c06\u5176\u5305\u88c5\u5728 usememo \u4e2d\uff0c\u5b83\u4ec5\u5728\u6570\u5b57\u6570\u7ec4\u66f4\u6539\u65f6\u8fd0\u884c\uff0c\u800c\u4e0d\u662f\u5728\u6bcf\u6b21\u6e32\u67d3\u65f6\u8fd0\u884c\u3002<\/p>\n
 2. \u907f\u514d\u91cd\u65b0\u521b\u5efa\u5bf9\u8c61\u6216\u6570\u7ec4 <\/h2>\n
\u5728\u6bcf\u6b21\u6e32\u67d3\u65f6\u5c06\u65b0\u7684\u6570\u7ec4\u6216\u5bf9\u8c61\u4f5c\u4e3a\u9053\u5177\u4f20\u9012\u7ed9\u5b50\u7ec4\u4ef6\u53ef\u80fd\u4f1a\u5bfc\u81f4\u4e0d\u5fc5\u8981\u7684\u91cd\u65b0\u6e32\u67d3\uff0c\u5373\u4f7f\u5185\u5bb9\u6ca1\u6709\u66f4\u6539\u3002 usememo \u53ef\u7528\u4e8e\u8bb0\u5fc6\u6570\u7ec4\u6216\u5bf9\u8c61\u3002<\/p>\n
import react, { usememo } from 'react';\n\nfunction childcomponent({ items }) {\n  console.log('child component re-rendered');\n  return (\n    <ul>\n      {items.map((item, index) => (\n        <li key={index}>{item}<\/li>\n      ))}\n    <\/ul>\n  );\n}\n\nexport default function parentcomponent() {\n  const items = usememo(() => ['apple', 'banana', 'cherry'], []);\n\n  return (\n    <div>\n      <h2>fruit list<\/h2>\n      <childcomponent items={items} \/>\n    <\/div>\n  );\n}\n<\/pre>\n
\u8fd9\u91cc\uff0c\u4f7f\u7528 usememo \u8bb0\u5fc6 items \u6570\u7ec4\uff0c\u786e\u4fdd childcomponent \u4ec5\u5728\u5fc5\u8981\u65f6\u91cd\u65b0\u6e32\u67d3\u3002\u5982\u679c\u6ca1\u6709 usememo\uff0c\u6bcf\u6b21\u6e32\u67d3\u90fd\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u6570\u7ec4\uff0c\u4ece\u800c\u5bfc\u81f4\u5b50\u7ec4\u4ef6\u4e0d\u5fc5\u8981\u7684\u91cd\u65b0\u6e32\u67d3\u3002<\/p>\n
 3. \u4f18\u5316\u5927\u578b\u7ec4\u4ef6\u6811 <\/h2>\n
\u4f7f\u7528\u5927\u578b\u7ec4\u4ef6\u6811\u65f6\uff0c\u4f7f\u7528 usememo \u53ef\u4ee5\u5e2e\u52a9\u51cf\u5c11\u4e0d\u5fc5\u8981\u7684\u91cd\u65b0\u6e32\u67d3\uff0c\u7279\u522b\u662f\u5bf9\u4e8e\u6df1\u5ea6\u5d4c\u5957\u7ec4\u4ef6\u4e2d\u6602\u8d35\u7684\u64cd\u4f5c\u3002<\/p>\n
import react, { usememo } from 'react';\n\nfunction largecomponenttree({ data }) {\n  const processeddata = usememo(() => {\n    console.log('processing data for large component tree...');\n    return data.map(item => ({ ...item, processed: true }));\n  }, [data]);\n\n  return (\n    <div>\n      <h2>processed data<\/h2>\n      {processeddata.map((item, index) => (\n        <div key={index}>{item.name}<\/div>\n      ))}\n    <\/div>\n  );\n}\n\n\/\/ usage\nconst largedataset = array.from({ length: 1000 }, (_, i) => ({ name: `item ${i + 1}` }));\nexport default function app() {\n  return <largecomponenttree data={largedataset} \/>;\n}\n<\/pre>\n
\u5728\u6b64\u793a\u4f8b\u4e2d\uff0cusememo \u7528\u4e8e\u5728\u5c06\u5927\u578b\u6570\u636e\u96c6\u6e32\u67d3\u5230\u7ec4\u4ef6\u4e2d\u4e4b\u524d\u5bf9\u5176\u8fdb\u884c\u5904\u7406\u3002\u901a\u8fc7\u8bb0\u5fc6\u5904\u7406\u540e\u7684\u6570\u636e\uff0c\u7ec4\u4ef6\u4ec5\u5728\u539f\u59cb data prop \u66f4\u6539\u65f6\u91cd\u65b0\u8ba1\u7b97\u6570\u636e\uff0c\u907f\u514d\u4e86\u4e0d\u5fc5\u8981\u7684\u91cd\u65b0\u5904\u7406\u5e76\u63d0\u9ad8\u4e86\u6027\u80fd\u3002<\/p>\n
 usememo \u7684\u6700\u4f73\u5b9e\u8df5 <\/h2>\n
\u867d\u7136 usememo \u662f\u4e00\u4e2a\u5f3a\u5927\u7684\u5de5\u5177\uff0c\u4f46\u6b63\u786e\u4f7f\u7528\u5b83\u4e5f\u5f88\u91cd\u8981\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u6700\u4f73\u5b9e\u8df5\uff1a<\/p>\n
    \n
  1. \u7528\u5b83\u6765\u4f18\u5316\u6027\u80fd\uff1a \u6602\u8d35\u7684\u8ba1\u7b97\u662f\u4f55\u65f6\u4f7f\u7528 usememo \u7684\u4e00\u4e2a\u5f88\u597d\u7684\u4f8b\u5b50\u3002\u5b83\u6267\u884c\u4e00\u4e2a\u53ef\u80fd\u6602\u8d35\u7684\u64cd\u4f5c\uff08\u5bf9\u6570\u7ec4\u6c42\u548c\u5e76\u5c06\u7ed3\u679c\u76f8\u4e58\uff09\uff0c\u8be5\u64cd\u4f5c\u53d6\u51b3\u4e8e\u6570\u5b57\u548c\u4e58\u6cd5\u5668\u72b6\u6001\u53d8\u91cf\u3002 <\/li>\n<\/ol>\n
    const expensivecalculation = usememo(() => {\n  console.log('calculating sum...');\n  return numbers.reduce((acc, num) => acc + num, 0) * multiplier;\n}, [numbers, multiplier]);\n<\/pre>\n
    \u6b64\u8ba1\u7b97\u53ea\u4f1a\u5728\u6570\u5b57\u6216\u4e58\u6570\u53d1\u751f\u53d8\u5316\u65f6\u91cd\u65b0\u8fd0\u884c\uff0c\u53ef\u80fd\u4f1a\u8282\u7701\u5176\u4ed6\u91cd\u65b0\u6e32\u67d3\u65f6\u4e0d\u5fc5\u8981\u7684\u91cd\u65b0\u8ba1\u7b97\u3002<\/p>\n
      \n
    1. \u4fdd\u6301\u4f9d\u8d56\u5173\u7cfb\u51c6\u786e\uff1a \u8bf7\u6ce8\u610f\u6602\u8d35\u8ba1\u7b97\u7684 usememo \u6302\u94a9\u5982\u4f55\u5728\u5176\u4f9d\u8d56\u9879\u6570\u7ec4\u4e2d\u5305\u542b\u6570\u5b57\u548c\u4e58\u6570\u3002\u8fd9\u53ef\u786e\u4fdd\u6bcf\u5f53\u8fd9\u4e9b\u503c\u53d1\u751f\u53d8\u5316\u65f6\u90fd\u4f1a\u91cd\u65b0\u8fd0\u884c\u8ba1\u7b97\u3002 <\/li>\n<\/ol>\n
      }, [numbers, multiplier]);  \/\/ correct dependencies\n<\/pre>\n
      \u5982\u679c\u6211\u4eec\u4ece\u4f9d\u8d56\u9879\u4e2d\u7701\u7565\u4e86\u4e58\u6570\uff0c\u5f53\u4e58\u6570\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u8ba1\u7b97\u5c06\u4e0d\u4f1a\u66f4\u65b0\uff0c\u4ece\u800c\u5bfc\u81f4\u9519\u8bef\u7684\u7ed3\u679c\u3002<\/p>\n
        \n
      1. \u4e0d\u8981\u8fc7\u5ea6\u4f7f\u7528 usememo\uff1a simplevalue \u793a\u4f8b\u663e\u793a\u4e86 usememo \u7684\u4e0d\u5fc5\u8981\u4f7f\u7528\uff1a <\/li>\n<\/ol>\n
        const simplevalue = usememo(() => {\n  return 42;  \/\/ this is not a complex calculation\n}, []);  \/\/ empty dependencies array\n<\/pre>\n
        \u8fd9\u79cd\u8bb0\u5fc6\u662f\u4e0d\u5fc5\u8981\u7684\uff0c\u56e0\u4e3a\u8be5\u503c\u662f\u5e38\u6570\u5e76\u4e14\u8ba1\u7b97\u5f88\u7b80\u5355\u3002\u5b83\u589e\u52a0\u4e86\u590d\u6742\u6027\uff0c\u4f46\u6ca1\u6709\u4efb\u4f55\u6027\u80fd\u4f18\u52bf\u3002<\/p>\n
          \n
        1. \u4e86\u89e3\u4f55\u65f6\u4e0d\u4f7f\u7528\u5b83\uff1a handleclick \u51fd\u6570\u662f\u4f55\u65f6\u4e0d\u4f7f\u7528 usememo \u7684\u4e00\u4e2a\u5f88\u597d\u7684\u793a\u4f8b\uff1a <\/li>\n<\/ol>\n
          const handleClick = () => {\n  console.log('Button clicked');\n};\n<\/pre>\n
          \u8fd9\u4e2a\u51fd\u6570\u5f88\u7b80\u5355\uff0c\u4e0d\u6d89\u53ca\u4efb\u4f55\u7e41\u91cd\u7684\u8ba1\u7b97\u3002\u8bb0\u4f4f\u5b83\u4f1a\u7ed9\u4ee3\u7801\u589e\u52a0\u4e0d\u5fc5\u8981\u7684\u590d\u6742\u6027\uff0c\u800c\u4e0d\u4f1a\u63d0\u4f9b\u4efb\u4f55\u663e\u7740\u7684\u6027\u80fd\u6539\u8fdb\u3002<\/p>\n
          \u901a\u8fc7\u9075\u5faa\u8fd9\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u60a8\u53ef\u4ee5\u6709\u6548\u5730\u4f7f\u7528 usememo \u6765\u4f18\u5316\u60a8\u7684 react \u7ec4\u4ef6\uff0c\u800c\u4e0d\u4f1a\u4f7f\u4ee3\u7801\u8fc7\u4e8e\u590d\u6742\u6216\u56e0\u4e0d\u6b63\u786e\u7684\u4f9d\u8d56\u7ba1\u7406\u800c\u5f15\u5165\u6f5c\u5728\u7684\u9519\u8bef\u3002<\/p>\n
           \u8981\u907f\u514d\u7684\u5e38\u89c1\u9677\u9631 <\/h2>\n
          \u867d\u7136 usememo \u662f\u4e00\u4e2a\u5f88\u68d2\u7684\u5de5\u5177\uff0c\u4f46\u6709\u4e00\u4e9b\u5e38\u89c1\u9519\u8bef\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n
            \n
          1. \n
            \u5ffd\u7565\u4f9d\u8d56\u5173\u7cfb\uff1a\u5982\u679c\u60a8\u5fd8\u8bb0\u5728\u6570\u7ec4\u4e2d\u5305\u542b\u4f9d\u8d56\u5173\u7cfb\uff0c\u5219\u8bb0\u5fc6\u7684\u503c\u53ef\u80fd\u4f1a\u53d8\u5f97\u8fc7\u65f6\uff0c\u4ece\u800c\u5bfc\u81f4\u9519\u8bef\u3002\u59cb\u7ec8\u4ed4\u7ec6\u68c0\u67e5\u8bb0\u5fc6\u51fd\u6570\u4e2d\u4f7f\u7528\u7684\u6240\u6709\u53d8\u91cf\u662f\u5426\u90fd\u5305\u542b\u5728\u4f9d\u8d56\u9879\u6570\u7ec4\u4e2d\u3002<\/p>\n<\/li>\n
          2. \n
            \u5230\u5904\u4f7f\u7528 usememo\uff1a\u5e76\u975e\u6bcf\u4e2a\u51fd\u6570\u6216\u503c\u90fd\u9700\u8981\u88ab\u8bb0\u5fc6\u3002\u5982\u679c\u60a8\u7684\u4ee3\u7801\u6ca1\u6709\u6027\u80fd\u95ee\u9898\uff0c\u6dfb\u52a0 usememo \u4e0d\u4f1a\u6539\u5584\u60c5\u51b5\u3002\u4e8b\u5b9e\u4e0a\uff0c\u7531\u4e8e\u8bb0\u5fc6\u7684\u5f00\u9500\uff0c\u5b83\u53ef\u80fd\u4f1a\u7a0d\u5fae\u51cf\u6162\u901f\u5ea6\u3002<\/p>\n<\/li>\n
          3. \n
            \u5bf9\u91cd\u65b0\u6e32\u67d3\u7684\u8bef\u89e3\uff1ausememo \u4ec5\u4f18\u5316\u8bb0\u5fc6\u5316\u8ba1\u7b97\uff0c\u800c\u4e0d\u662f\u7ec4\u4ef6\u7684\u6574\u4e2a\u6e32\u67d3\u8fc7\u7a0b\u3002\u5982\u679c\u7ec4\u4ef6\u4ecd\u7136\u6536\u5230\u65b0\u7684 props \u6216\u72b6\u6001\uff0c\u5373\u4f7f\u8bb0\u5fc6\u7684\u503c\u6ca1\u6709\u6539\u53d8\uff0c\u5b83\u4e5f\u4f1a\u91cd\u65b0\u6e32\u67d3\u3002<\/p>\n<\/li>\n<\/ol>\n
             \u7ed3\u8bba <\/h2>\n
            usememo \u662f\u4e00\u4e2a\u7528\u4e8e\u4f18\u5316 react \u5e94\u7528\u7a0b\u5e8f\u6027\u80fd\u7684\u5f3a\u5927\u94a9\u5b50\uff0c\u4f46\u5e94\u8be5\u660e\u667a\u5730\u4f7f\u7528\u5b83\u3002\u4e13\u6ce8\u4e8e\u5728\u5b58\u5728\u771f\u6b63\u6027\u80fd\u74f6\u9888\u7684\u5730\u65b9\u4f7f\u7528\u5b83\uff0c\u5e76\u59cb\u7ec8\u786e\u4fdd\u60a8\u7684\u4f9d\u8d56\u9879\u662f\u6b63\u786e\u7684\u3002\u901a\u8fc7\u9075\u5faa\u8fd9\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u60a8\u53ef\u4ee5\u907f\u514d\u5e38\u89c1\u7684\u9677\u9631\u5e76\u5728\u9879\u76ee\u4e2d\u5145\u5206\u5229\u7528 usememo\u3002<\/p>\n
            \u672c\u7bc7\u5173\u4e8e\u300a\u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5\u300b\u7684\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\u5566\uff0c\u4f46\u662f\u5b66\u65e0\u6b62\u5883\uff0c\u60f3\u8981\u4e86\u89e3\u5b66\u4e60\u66f4\u591a\u5173\u4e8e\u6587\u7ae0\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u8bf7\u5173\u6ce8\u7c73\u4e91\u516c\u4f17\u53f7\uff01<\/p>\n
                  \u7248\u672c\u58f0\u660e \u672c\u6587\u8f6c\u8f7d\u4e8e\uff1adev.to \u5982\u6709\u4fb5\u72af\uff0c\u8bf7\u8054\u7cfb\u5220\u9664    <\/p>\n
            \n
            <\/dt>\n
            \n   \u6279\u91cf\u63d2\u5165\u51fa\u9519\u65f6\u5982\u4f55\u8df3\u8fc7\u9519\u8bef\u6570\u636e\u7ee7\u7eed\u63d2\u5165\uff1f\n <\/dd>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
            \u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5 \u6536\u85cf \u6700\u8fd1\u53d1\u73b0\u4e0d\u5c11\u5c0f\u4f19\u4f34\u90fd\u5bf9\u6587\u7ae0\u5f88\u611f\u5174\u8da3\uff0c\u6240\u4ee5\u4eca\u5929\u7ee7\u7eed\u7ed9\u5927\u5bb6\u4ecb\u7ecd\u6587\u7ae0\u76f8\u5173\u7684\u77e5\u8bc6\uff0c\u672c\u6587\u300a\u4e86\u89e3 React \u7684 useMemo\uff1a\u5b83\u7684\u4f5c\u7528\u3001\u4f55\u65f6\u4f7f\u7528\u5b83\u4ee5\u53ca\u6700\u4f73\u5b9e\u8df5\u300b\u4e3b\u8981\u5185\u5bb9\u6d89\u53ca\u5230\u7b49\u7b49\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u80fd\u5e2e\u5230\u4f60\uff01\u5f53\u7136\u5982\u679c\u9605\u8bfb\u672c\u6587\u65f6\u5b58\u5728\u4e0d\u540c\u60f3\u6cd5\uff0c\u53ef\u4ee5\u5728\u8bc4\u8bba\u4e2d\u8868\u8fbe\uff0c\u4f46\u662f\u8bf7\u52ff\u4f7f\u7528\u8fc7\u6fc0\u7684\u63aa\u8f9e~ react \u662f\u4e00\u4e2a\u7528\u4e8e\u6784\u5efa\u7528\u6237\u754c\u9762\u7684\u5f3a\u5927\u5e93\uff0c\u4f46\u968f\u7740\u5e94\u7528\u7a0b\u5e8f\u7684\u589e\u957f\uff0c\u60a8\u53ef\u80fd\u4f1a\u6ce8\u610f\u5230\u6027\u80fd\u6709\u65f6\u4f1a\u6210\u4e3a\u95ee\u9898\u3002\u8fd9\u5c31\u662f\u50cf usememo \u8fd9\u6837\u7684 react hook \u53d1\u6325\u4f5c\u7528\u7684\u5730\u65b9\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u6df1\u5165\u63a2\u8ba8 usememo \u7684\u4f5c\u7528\u3001\u4f55\u65f6\u6709\u7528\u4ee5\u53ca\u4f7f\u7528\u5b83\u7684\u6700\u4f73\u5b9e\u8df5\u3002\u6211\u4eec\u8fd8\u5c06\u4ecb\u7ecd\u4e00\u4e9b\u9700\u8981\u907f\u514d\u7684\u5e38\u89c1\u9677\u9631\u3002 \u4ec0\u4e48\u662f usememo\uff1f usememo \u662f\u4e00\u4e2a react hook\uff0c\u5141\u8bb8\u4f60\u8bb0\u4f4f\u8ba1\u7b97\u7ed3\u679c\u3002\u7b80\u5355\u6765\u8bf4\uff0c\u5b83\u4f1a\u8bb0\u4f4f\u51fd\u6570\u7684\u7ed3\u679c\uff0c\u5e76\u4e14\u4ec5\u5728\u5176\u4f9d\u8d56\u9879\u53d1\u751f\u53d8\u5316\u65f6\u624d\u91cd\u65b0\u8ba1\u7b97\u5b83\u3002\u8fd9\u53ef\u4ee5\u9632\u6b62\u4e0d\u5fc5\u8981\u7684\u8ba1\u7b97\u5e76\u63d0\u9ad8\u6027\u80fd\u3002 \u8fd9\u662f\u4e00\u4e2a\u57fa\u672c\u793a\u4f8b\uff1a import react, { usememo } from ‘react’; function expensivecalculation({ num }) { const result = usememo(() => { console.log(‘calculating…’); return num * 2; }, [num]); return <div>the result is {result}<\/div>; […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-53067","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/53067","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=53067"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/53067\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=53067"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=53067"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=53067"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}