React 编译器

React Compiler 是一个我们已将其开源以获得社区的早期反馈的新编译器。它是一个仅构建时的工具，可以自动优化你的 React 应用。它使用纯 JavaScript，并理解 React 的规则，因此你无需重写任何代码即可使用它。

¥React Compiler is a new compiler that we’ve open sourced to get early feedback from the community. It is a build-time only tool that automatically optimizes your React app. It works with plain JavaScript, and understands the Rules of React, so you don’t need to rewrite any code to use it.

编译器还包括一个 ESLint 插件，可以在编辑器中直接显示编译器的分析结果。我们强烈建议大家今天就使用 linter。linter 不需要你安装编译器，因此即使你还没有准备好试用编译器，也可以使用它。

¥The compiler also includes an ESLint plugin that surfaces the analysis from the compiler right in your editor. We strongly recommend everyone use the linter today. The linter does not require that you have the compiler installed, so you can use it even if you are not ready to try out the compiler.

编译器目前以 beta 的形式发布，可在 React 17+ 应用和库上试用。要安装 Beta 版：

¥The compiler is currently released as beta, and is available to try out on React 17+ apps and libraries. To install the Beta:

或者，如果你使用的是 Yarn：

¥Or, if you’re using Yarn:

如果你尚未使用 React 19，请参阅 以下部分 以获取进一步说明。

¥If you are not using React 19 yet, please see the section below for further instructions.

编译器做什么？

¥What does the compiler do?

为了优化应用，React Compiler 会自动记忆你的代码。你今天可能熟悉通过 useMemo、useCallback 和 React.memo 等 API 进行记忆化。使用这些 API，你可以告诉 React，如果应用的某些部分的输入没有改变，则不需要重新计算，从而减少更新工作。虽然功能强大，但很容易忘记应用记忆或错误地应用它们。这可能会导致更新效率低下，因为 React 必须检查 UI 中没有任何有意义更改的部分。

¥In order to optimize applications, React Compiler automatically memoizes your code. You may be familiar today with memoization through APIs such as useMemo, useCallback, and React.memo. With these APIs you can tell React that certain parts of your application don’t need to recompute if their inputs haven’t changed, reducing work on updates. While powerful, it’s easy to forget to apply memoization or apply them incorrectly. This can lead to inefficient updates as React has to check parts of your UI that don’t have any meaningful changes.

编译器使用其对 JavaScript 和 React 规则的了解来自动记忆组件和钩子内的值或值组。如果它检测到规则的破坏，它将自动跳过这些组件或钩子，并继续安全地编译其他代码。

¥The compiler uses its knowledge of JavaScript and React’s rules to automatically memoize values or groups of values within your components and hooks. If it detects breakages of the rules, it will automatically skip over just those components or hooks, and continue safely compiling other code.

如果你的代码库已经很好地进行了记忆，你可能不会期望编译器会带来重大的性能改进。然而，在实践中，手动记住导致性能问题的正确依赖是很棘手的。

¥If your codebase is already very well-memoized, you might not expect to see major performance improvements with the compiler. However, in practice memoizing the correct dependencies that cause performance issues is tricky to get right by hand.

function FriendList({ friends }) {
  const onlineCount = useFriendOnlineCount();
  if (friends.length === 0) {
    return <NoFriends />;
  }
  return (
    <div>
      <span>{onlineCount} online</span>
      {friends.map((friend) => (
        <FriendListCard key={friend.id} friend={friend} />
      ))}
      <MessageButton />
    </div>
  );
}

// **Not** memoized by React Compiler, since this is not a component or hook
function expensivelyProcessAReallyLargeArrayOfObjects() { /* ... */ }

// Memoized by React Compiler since this is a component
function TableContainer({ items }) {
  // This function call would be memoized:
  const data = expensivelyProcessAReallyLargeArrayOfObjects(items);
  // ...
}

我应该尝试一下编译器吗？

¥Should I try out the compiler?

请注意，编译器仍处于测试阶段，有许多粗糙之处。虽然它已在 Meta 等公司的生产中使用，但将编译器推出到你的应用的生产中将取决于你的代码库的运行状况以及你遵循 React 的规则 的程度。

¥Please note that the compiler is still in Beta and has many rough edges. While it has been used in production at companies like Meta, rolling out the compiler to production for your app will depend on the health of your codebase and how well you’ve followed the Rules of React.

你现在不必急于使用编译器。可以等到它达到稳定版本后再采用它。不过，我们非常感谢你在应用中进行小实验，以便你可以向我们提供帮助，以帮助改进编译器。

¥You don’t have to rush into using the compiler now. It’s okay to wait until it reaches a stable release before adopting it. However, we do appreciate trying it out in small experiments in your apps so that you can provide feedback to us to help make the compiler better.

入门

¥Getting Started

除了这些文档之外，我们建议检查 React 编译器工作组 以获取有关编译器的其他信息和讨论。

¥In addition to these docs, we recommend checking the React Compiler Working Group for additional information and discussion about the compiler.

安装 eslint-plugin-react-compiler

¥Installing eslint-plugin-react-compiler

React Compiler 还支持 ESLint 插件。ESLint 插件可以独立于编译器使用，这意味着即使你不使用编译器，也可以使用 ESLint 插件。

¥React Compiler also powers an ESLint plugin. The ESLint plugin can be used independently of the compiler, meaning you can use the ESLint plugin even if you don’t use the compiler.

然后，将其添加到你的 ESLint 配置中：

¥Then, add it to your ESLint config:

import reactCompiler from 'eslint-plugin-react-compiler'

export default [
  {
    plugins: {
      'react-compiler': reactCompiler,
    },
    rules: {
      'react-compiler/react-compiler': 'error',
    },
  },
]

或者，在弃用的 eslintrc 配置格式中：

¥Or, in the deprecated eslintrc config format:

module.exports = {
  plugins: [
    'eslint-plugin-react-compiler',
  ],
  rules: {
    'react-compiler/react-compiler': 'error',
  },
}

ESLint 插件将在你的编辑器中显示任何违反 React 规则的行为。当它这样做时，意味着编译器跳过了优化该组件或钩子。这完全没问题，编译器可以恢复并继续优化代码库中的其他组件。

¥The ESLint plugin will display any violations of the rules of React in your editor. When it does this, it means that the compiler has skipped over optimizing that component or hook. This is perfectly okay, and the compiler can recover and continue optimizing other components in your codebase.

将编译器推出到你的代码库

¥Rolling out the compiler to your codebase

现有项目

¥Existing projects

该编译器旨在编译遵循 React 的规则 的功能组件和钩子。它还可以通过退出（跳过）这些组件或钩子来处理违反这些规则的代码。然而，由于 JavaScript 的灵活性，编译器无法捕获所有可能的违规行为，并且可能会出现误报：也就是说，编译器可能会意外编译一个违反 React 规则的组件/钩子，从而导致未定义的行为。

¥The compiler is designed to compile functional components and hooks that follow the Rules of React. It can also handle code that breaks those rules by bailing out (skipping over) those components or hooks. However, due to the flexible nature of JavaScript, the compiler cannot catch every possible violation and may compile with false negatives: that is, the compiler may accidentally compile a component/hook that breaks the Rules of React which can lead to undefined behavior.

因此，为了在现有项目中成功采用编译器，我们建议首先在产品代码中的一个小目录中运行它。你可以通过将编译器配置为仅在一组特定目录上运行来实现此目的：

¥For this reason, to adopt the compiler successfully on existing projects, we recommend running it on a small directory in your product code first. You can do this by configuring the compiler to only run on a specific set of directories:

const ReactCompilerConfig = {
  sources: (filename) => {
    return filename.indexOf('src/path/to/dir') !== -1;
  },
};

当你对推出编译器更有信心时，你也可以将覆盖范围扩大到其他目录，并慢慢将其推广到整个应用。

¥When you have more confidence with rolling out the compiler, you can expand coverage to other directories as well and slowly roll it out to your whole app.

新项目

¥New projects

如果你要开始一个新项目，你可以在整个代码库上启用编译器，这是默认行为。

¥If you’re starting a new project, you can enable the compiler on your entire codebase, which is the default behavior.

将 React 编译器与 React 17 或 18 结合使用

¥Using React Compiler with React 17 or 18

React Compiler 与 React 19 RC 配合使用效果最佳。如果你无法升级，你可以安装额外的 react-compiler-runtime 包，这将允许编译后的代码在 19 之前的版本上运行。但是，请注意，支持的最低版本是 17。

¥React Compiler works best with React 19 RC. If you are unable to upgrade, you can install the extra react-compiler-runtime package which will allow the compiled code to run on versions prior to 19. However, note that the minimum supported version is 17.

你还应该将正确的 target 添加到你的编译器配置中，其中 target 是你要定位的 React 的主要版本：

¥You should also add the correct target to your compiler config, where target is the major version of React you are targeting:

// babel.config.js
const ReactCompilerConfig = {
  target: '18' // '17' | '18' | '19'
};

module.exports = function () {
  return {
    plugins: [
      ['babel-plugin-react-compiler', ReactCompilerConfig],
    ],
  };
};

在库

¥Using the compiler on libraries

React Compiler 还可用于编译库。由于 React Compiler 需要在进行任何代码转换之前在原始源代码上运行，因此应用的构建管道无法编译它们使用的库。因此，我们建议库维护者使用编译器独立编译和测试他们的库，并将编译后的代码发送到 npm。

¥React Compiler can also be used to compile libraries. Because React Compiler needs to run on the original source code prior to any code transformations, it is not possible for an application’s build pipeline to compile the libraries they use. Hence, our recommendation is for library maintainers to independently compile and test their libraries with the compiler, and ship compiled code to npm.

因为你的代码是预编译的，所以你的库的用户不需要启用编译器就可以从应用于你的库的自动记忆中受益。如果你的库针对尚未在 React 19 上运行的应用，请指定最低 target 并添加 react-compiler-runtime 作为直接依赖。运行时包将根据应用的版本使用正确的 API 实现，并在必要时填充缺少的 API。

¥Because your code is pre-compiled, users of your library will not need to have the compiler enabled in order to benefit from the automatic memoization applied to your library. If your library targets apps not yet on React 19, specify a minimum target and add react-compiler-runtime as a direct dependency. The runtime package will use the correct implementation of APIs depending on the application’s version, and polyfill the missing APIs if necessary.

库代码通常需要更复杂的模式和逃生舱的使用。因此，我们建议确保你进行了足够的测试，以便识别使用库上的编译器可能出现的任何问题。如果你发现任何问题，你可以随时选择退出 'use no memo' 指令 的特定组件或钩子。

¥Library code can often require more complex patterns and usage of escape hatches. For this reason, we recommend ensuring that you have sufficient testing in order to identify any issues that might arise from using the compiler on your library. If you identify any issues, you can always opt-out the specific components or hooks with the 'use no memo' directive.

与应用类似，无需完全编译 100% 的组件或钩子即可在库中看到好处。一个好的起点可能是确定库中最对性能敏感的部分，并确保它们不会破坏 React 的规则，你可以使用 eslint-plugin-react-compiler 来识别。

¥Similarly to apps, it is not necessary to fully compile 100% of your components or hooks to see benefits in your library. A good starting point might be to identify the most performance sensitive parts of your library and ensuring that they don’t break the Rules of React, which you can use eslint-plugin-react-compiler to identify.

用法

¥Usage

Babel

编译器包含一个 Babel 插件，你可以在构建管道中使用该插件来运行编译器。

¥The compiler includes a Babel plugin which you can use in your build pipeline to run the compiler.

安装后，将其添加到 Babel 配置中。请注意，编译器首先在管道中运行至关重要：

¥After installing, add it to your Babel config. Please note that it’s critical that the compiler run first in the pipeline:

// babel.config.js
const ReactCompilerConfig = { /* ... */ };

module.exports = function () {
  return {
    plugins: [
      ['babel-plugin-react-compiler', ReactCompilerConfig], // must run first!
      // ...
    ],
  };
};

babel-plugin-react-compiler 应该先于其他 Babel 插件运行，因为编译器需要输入源信息进行声音分析。

¥babel-plugin-react-compiler should run first before other Babel plugins as the compiler requires the input source information for sound analysis.

Vite

如果你使用 Vite，可以将插件添加到 vite-plugin-react 中：

¥If you use Vite, you can add the plugin to vite-plugin-react:

// vite.config.js
const ReactCompilerConfig = { /* ... */ };

export default defineConfig(() => {
  return {
    plugins: [
      react({
        babel: {
          plugins: [
            ["babel-plugin-react-compiler", ReactCompilerConfig],
          ],
        },
      }),
    ],
    // ...
  };
});

Next.js

有关更多信息，请参阅 Next.js 文档。

¥Please refer to the Next.js docs for more information.

Remix

安装 vite-plugin-babel，并添加编译器的 Babel 插件：

¥Install vite-plugin-babel, and add the compiler’s Babel plugin to it:

// vite.config.js
import babel from "vite-plugin-babel";

const ReactCompilerConfig = { /* ... */ };

export default defineConfig({
  plugins: [
    remix({ /* ... */}),
    babel({
      filter: /\.[jt]sx?$/,
      babelConfig: {
        presets: ["@babel/preset-typescript"], // if you use TypeScript
        plugins: [
          ["babel-plugin-react-compiler", ReactCompilerConfig],
        ],
      },
    }),
  ],
});

Webpack

社区 Webpack 加载器是 现在可在此处使用。

¥A community Webpack loader is now available here.

Expo

请参阅 Expo 的文档 以在 Expo 应用中启用和使用 React 编译器。

¥Please refer to Expo’s docs to enable and use the React Compiler in Expo apps.

Metro (React Native)

React Native 通过 Metro 使用 Babel，因此请参阅 与 Babel 一起使用 部分以获取安装说明。

¥React Native uses Babel via Metro, so refer to the Usage with Babel section for installation instructions.

Rspack

请参阅 Rspack 的文档 以在 Rspack 应用中启用和使用 React 编译器。

¥Please refer to Rspack’s docs to enable and use the React Compiler in Rspack apps.

Rsbuild

请参阅 Rsbuild 的文档 以在 Rsbuild 应用中启用和使用 React 编译器。

¥Please refer to Rsbuild’s docs to enable and use the React Compiler in Rsbuild apps.

故障排除

¥Troubleshooting

要报告问题，请首先在 React 编译器在线运行 上创建一个最小的重现并将其包含在你的错误报告中。你可以在 facebook/react 存储库中打开问题。

¥To report issues, please first create a minimal repro on the React Compiler Playground and include it in your bug report. You can open issues in the facebook/react repo.

你还可以通过申请成为成员来在 React 编译器工作组中提供反馈。请参阅 有关加入的更多详细信息，请参阅自述文件。

¥You can also provide feedback in the React Compiler Working Group by applying to be a member. Please see the README for more details on joining.

编译器假设什么？

¥What does the compiler assume?

React Compiler 假设你的代码：

¥React Compiler assumes that your code:

1. 是有效的语义 JavaScript。

   ¥Is valid, semantic JavaScript.

2. 在访问可空/可选值和属性之前测试它们是否已定义（例如，如果使用 TypeScript，则通过启用 strictNullChecks），即 if (object.nullableProperty) { object.nullableProperty.foo } 或使用可选链 object.nullableProperty?.foo。

   ¥Tests that nullable/optional values and properties are defined before accessing them (for example, by enabling strictNullChecks if using TypeScript), i.e., if (object.nullableProperty) { object.nullableProperty.foo } or with optional-chaining object.nullableProperty?.foo.

3. 遵循 React 的规则。

   ¥Follows the Rules of React.

React Compiler 可以静态验证 React 的许多规则，并在检测到错误时安全地跳过编译。要查看错误，我们还建议安装 eslint-plugin-react-compiler。

¥React Compiler can verify many of the Rules of React statically, and will safely skip compilation when it detects an error. To see the errors we recommend also installing eslint-plugin-react-compiler.

我如何知道我的组件已经优化？

¥How do I know my components have been optimized?

React Devtools (v5.0+) 内置了对 React Compiler 的支持，并将在编译器已优化的组件旁边显示 “备忘录 ✨” 徽章。

¥React Devtools (v5.0+) has built-in support for React Compiler and will display a “Memo ✨” badge next to components that have been optimized by the compiler.

编译后某些东西不起作用

¥Something is not working after compilation

如果你安装了 eslint-plugin-react-compiler，编译器将在你的编辑器中显示任何违反 React 规则的行为。当它这样做时，意味着编译器跳过了优化该组件或钩子。这完全没问题，编译器可以恢复并继续优化代码库中的其他组件。你不必立即修复所有 ESLint 违规行为。你可以按照自己的节奏解决这些问题，以增加要优化的组件和钩子的数量。

¥If you have eslint-plugin-react-compiler installed, the compiler will display any violations of the rules of React in your editor. When it does this, it means that the compiler has skipped over optimizing that component or hook. This is perfectly okay, and the compiler can recover and continue optimizing other components in your codebase. You don’t have to fix all ESLint violations straight away. You can address them at your own pace to increase the amount of components and hooks being optimized.

然而，由于 JavaScript 的灵活性和动态性，不可能全面检测所有情况。在这些情况下可能会出现错误和未定义的行为，例如无限循环。

¥Due to the flexible and dynamic nature of JavaScript however, it’s not possible to comprehensively detect all cases. Bugs and undefined behavior such as infinite loops may occur in those cases.

如果你的应用在编译后无法正常工作并且你没有看到任何 ESLint 错误，则编译器可能错误地编译了你的代码。为了确认这一点，请尝试通过积极选择退出你认为可能与 "use no memo" 指令 相关的任何组件或钩子来解决问题。

¥If your app doesn’t work properly after compilation and you aren’t seeing any ESLint errors, the compiler may be incorrectly compiling your code. To confirm this, try to make the issue go away by aggressively opting out any component or hook you think might be related via the "use no memo" directive.

function SuspiciousComponent() {
  "use no memo"; // opts out this component from being compiled by React Compiler
  // ...
}

当你使错误消失时，请确认删除 opt out 指令会使问题再次出现。然后使用 React 编译器在线运行 与我们分享错误报告（你可以尝试将其缩小为一个小型再现，或者如果它是开源代码，你也可以粘贴整个源代码），以便我们识别并帮助解决问题。

¥When you make the error go away, confirm that removing the opt out directive makes the issue come back. Then share a bug report with us (you can try to reduce it to a small repro, or if it’s open source code you can also just paste the entire source) using the React Compiler Playground so we can identify and help fix the issue.

其他事宜

¥Other issues

请参阅 https://github.com/reactwg/react-compiler/discussions/7。

¥Please see https://github.com/reactwg/react-compiler/discussions/7.