React Compiler

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. React Compiler 是一个新编译器，我们将其开源以获取社区的早期反馈。它是一个仅在构建时使用的工具，可以自动优化你的 React 应用程序。它可以与纯 JavaScript 一起使用，并且了解 React 规则，因此你无需重写任何代码即可使用它。

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. 编译器还包括一个 ESLint 插件，可以在你的编辑器中直接显示编译器的分析结果。我们强烈建议大家使用 linter。 不过 linter 并不需要安装编译器，因此即使你还没有准备好尝试编译器也可以使用它。

The compiler is currently released as beta, and is available to try out on React 17+ apps and libraries. To install the Beta: 编译器目前处于 beta 阶段，并且可以在 React 17+ 应用程序和库上使用。安装方式如下：

Or, if you’re using Yarn: 或者使用 Yarn：

If you are not using React 19 yet, please see the section below for further instructions. 如果你还没有使用 React 19，请参考 此内容 以获得进一步说明。

编译器是做什么的？| What does the compiler do?

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. 为了优化应用程序，React Compiler 会自动对你的代码进行记忆化处理。你可能已经熟悉了像 useMemo、useCallback 和 React.memo 这样的 API，通过这些 API，你可以告诉 React，如果输入没有发生变化，应用程序的某些部分不需要重新计算，从而减少更新时的工作量。虽然这些功能很强大，但很容易忘记应用记忆化或者错误地应用它们。这可能会导致更新效率低下，因为 React 必须检查 UI 中没有任何有意义的更改的部分。

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. 编译器利用其对 JavaScript 和 React 规则的了解，自动对组件和钩子中的值或值组进行记忆化。如果它检测到规则的破坏，它将自动跳过那些组件或钩子，并继续安全地编译其他代码。

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. 如果你的代码库已经非常好地进行了记忆化处理，你可能不会指望通过编译器看到主要的性能改进。然而，在实践中，手动正确记忆化导致性能问题的依赖关系是很棘手的。

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
// 由于这不是组件或钩子，React Compiler 不会进行记忆
function expensivelyProcessAReallyLargeArrayOfObjects() { /* ... */ }

// Memoized by React Compiler since this is a component
// 由 React Compiler 进行了记忆化，因为这是一个组件
function TableContainer({ items }) {
  // This function call would be memoized:
  // 这个函数调用将被记忆：
  const data = expensivelyProcessAReallyLargeArrayOfObjects(items);
  // ...
}

我应该尝试一下编译器吗？| Should I try out the compiler?

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. 请注意，编译器仍处于 Beta 阶段，存在许多不完善之处。虽然它已经在 Meta 等公司的生产环境中使用过，但将编译器应用于你的应用程序生产环境将取决于你的代码库的健康状况以及你是否遵循了 React 的规则。

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. 你现在不必急着使用编译器。在采用它之前等到它达到稳定版本是可以的。 然而，我们确实赞赏在你的应用程序中进行小型实验，以便你可以向我们 提供反馈，帮助使编译器更好。

开始 | Getting Started

In addition to these docs, we recommend checking the React Compiler Working Group for additional information and discussion about the compiler. 除了这些文档之外，我们还建议查看 React Compiler 工作组，以获取有关编译器的更多信息和讨论。

安装 eslint-plugin-react-compiler | Installing eslint-plugin-react-compiler

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. React Compiler 还为 ESLint 插件提供支持。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。

Then, add it to your ESLint config: 然后，将其添加到你的 ESLint 配置中：

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

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

Or, in the deprecated eslintrc config format: 或者使用已弃用的 eslintrc 配置格式：

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

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

将编译器应用到你的代码库 | Rolling out the compiler to your codebase

现有项目 | Existing projects

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. 编译器旨在编译遵循 React 规则的功能组件和钩子。它还可以处理违反这些规则的代码，通过跳过这些组件或钩子来终止执行。然而，由于JavaScript的灵活性，编译器无法捕捉到每一个可能的违规行为，可能会出现错误的负面编译：也就是说，编译器可能会意外地编译出一个违反 React 规则 的组件或钩子，这可能导致未定义的行为。

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: 因此，要在现有项目中成功采用编译器，我们建议你先在项目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的目录上运行来执行此操作：

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

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. 当你对编译器更有信心时，你也可以将覆盖范围扩展到其他目录，并逐渐将其推出到整个应用程序。

新项目 | New projects

If you’re starting a new project, you can enable the compiler on your entire codebase, which is the default behavior. 如果你正在启动一个新项目，你可以在整个代码库上启用编译器，这是默认行为。

在 React 17 或 18 中使用 React Compiler | Using React Compiler with React 17 or 18

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. React Compiler 与 React 19 RC 配合使用效果最佳。如果你无法升级，可以安装额外的 react-compiler-runtime 包来编译代码并在 19 之前的版本上运行。 但请注意，支持的最低版本是 17。

You should also add the correct target to your compiler config, where target is the major version of React you are targeting: 你还应该在编译器配置中添加正确的 target，值为你所使用的 React 大版本。

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

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

在库中使用 Compiler | Using the compiler on libraries

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. React Compiler 还可用于编译库。由于 React Compiler 需要在代码转换之前的源码上运行，因此应用程序无法使用 pipeline 来编译所使用的库。因此我们建议库维护人员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布到 npm。

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. 由于库的代码是预编译的，因此用户无需启用 Compiler 即可从编译器的自动记忆化中受益。如果库的 target 不是 React 19，请指定一个最小的 target 并且将 react-compiler-runtime 添加为直接依赖。这个运行时包将根据应用程序的版本使用正确的 API 实现，并在必要时填充缺失的 API。

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. 库代码通常需要更复杂的模式和脱围机制。因此我们建议你进行足够的测试，以便发现在在库中使用编译器时可能出现的任何问题。对于任何发现的问题都可以使用 'use no memo' 指令 来选择退出对特定组件或 Hook 的自动记忆化。

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. 与应用程序类似，无需 100% 编译组件或 Hook 就可以看到编译器带来的好处。一个好的起点可能是确定库中对性能最敏感的部分，并确保它们没有违反 React 规则，你可以通过使用 eslint-plugin-react-compiler 来完成。

用法 | Usage

Babel

The compiler includes a Babel plugin which you can use in your build pipeline to run the compiler. 编译器包含一个 Babel 插件，你可以在构建流水线中使用它来运行编译器。

After installing, add it to your Babel config. Please note that it’s critical that the compiler run first in the pipeline: 安装后，请将其添加到你的 Babel 配置中。请注意，编译器必须首先在流水线中运行。

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

module.exports = function () {
  return {
    plugins: [
      ['babel-plugin-react-compiler', ReactCompilerConfig], // 必须首先运行！
      // ...
    ],
  };
};

babel-plugin-react-compiler should run first before other Babel plugins as the compiler requires the input source information for sound analysis. babel-plugin-react-compiler 应该在其他 Babel 插件之前运行，因为编译器需要输入源信息进行声音分析。

Vite

If you use Vite, you can add the plugin to vite-plugin-react: 如果你使用 Vite，你可以将插件添加到 vite-plugin-react 中：

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

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

Next.js

Please refer to the Next.js docs for more information. 请参考 Next.js 文档 来了解更多信息。

Remix

Install vite-plugin-babel, and add the compiler’s Babel plugin to it: 安装 vite-plugin-babel, 并将编译器的 Babel 插件添加到其中：

// 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"], // 如果你使用 TypeScript
        plugins: [
          ["babel-plugin-react-compiler", ReactCompilerConfig],
        ],
      },
    }),
  ],
});

Webpack

A community Webpack loader is now available here. 由社区提供的 Webpack loader 可以 在这里找到。

Expo

Please refer to Expo’s docs to enable and use the React Compiler in Expo apps. 请参考 Expo 文档 应用程序中启用和使用 React Compiler。

Metro (React Native)

React Native uses Babel via Metro, so refer to the Usage with Babel section for installation instructions. React Native 通过 Metro 使用 Babel，因此请参考 使用 Babel 部分的安装说明。

Rspack

Please refer to Rspack’s docs to enable and use the React Compiler in Rspack apps. 请参考 Rspack 文档 以启用并在 Rspack 应用程序中使用 React Compiler。

Rsbuild

Please refer to Rsbuild’s docs to enable and use the React Compiler in Rsbuild apps. 请参考 Rsbuild 文档 以在 Rsbuild 应用程序中启用和使用 React Compiler。

疑难解答 | Troubleshooting

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. 请先在 React Compiler Playground 上创建一个最小的可复现问题，并将其包含在你的错误报告中。你可以在 facebook/react 仓库中提交 issue。

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. 你也可以通过申请成为成员，在 React Compiler 工作组中提供反馈意见。请查看 README 以获取更多加入详情。

编译器假设什么？| What does the compiler assume?

React Compiler assumes that your code: React Compiler 假设你的代码：

1. Is valid, semantic JavaScript.

• 是有效的，语义化的 JavaScript

2. 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.

• 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，则启用 strictNullChecks），即：if (object.nullableProperty) { object.nullableProperty.foo } 或者使用可选链 object.nullableProperty?.foo

3. Follows the Rules of React.

• 遵循 React 规则

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. React Compiler 可以静态验证 React 的许多规则，并且在检测到错误时会安全地跳过编译。要查看错误，我们建议同时安装 eslint-plugin-react-compiler。

我如何知道我的组件已被优化？| How do I know my components have been optimized?

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. React 开发工具（v5.0 及以上版本）对 React Compiler 有内置支持，并会在已被编译器优化的组件旁边显示“Memo ✨”徽章。

编译后某些内容无法正常工作 | Something is not working after compilation

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. 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 规则的情况。当它这样做时，意味着编译器跳过了对该组件或钩子的优化。这完全没问题，并且编译器可以恢复并继续优化你代码库中的其他组件。你不必立即修复所有的违反 ESLint 规则的代码。 你可以按照自己的节奏来处理它们，以增加被优化的组件和钩子的数量。

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. 然而，由于 JavaScript 的灵活和动态性质，不可能全面检测到所有情况。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。

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. 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，编译器可能错误地编译了你的代码。为了确认这一点，尝试通过积极选择你认为可能相关的任何组件或钩子，并通过 "use no memo" 指令 退出优化来解决问题。

function SuspiciousComponent() {
  "use no memo"; // 选择不让此组件由 React Compiler 进行编译 // opts out this component from being compiled by React Compiler
  // ...
}

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. 当你修复错误时，请确认删除退出指令是否会使问题重新出现。然后使用 React Compiler Playground 与我们分享一个错误报告（你可以尝试将其减少到一个小的重现，或者如果是开源代码，你也可以直接粘贴整个源代码），这样我们就可以识别并帮助解决问题。

其他问题 | Other issues

Please see https://github.com/reactwg/react-compiler/discussions/7. 请查阅 https://github.com/reactwg/react-compiler/discussions/7 。