React源码解读

配置React源码本地调试环境

本次环境构建采用了node版本为16、react-scripts 版本号为 3.4.4，源码下载地址 react源码调试: react源码调试环境

使用 create-react-app 脚手架创建项目

npx create-react-app react-test

进入刚刚下载的目录，弹射 create-react-app 脚手架内部配置

// 在 npm run eject 之前，手动将项目 package.json 里面 react-scripts 版本号改为低版本的 3.4.4，删除 node_modules 后重装，确保使用老版本脚手架
npm run eject

克隆 react 官方源码 (在项目的根目录下进行克隆)

git clone --branch v16.13.1 --depth=1 https://github.com/facebook/react.git src/react

接着链接本地源码

// 文件位置: react-test/config/webpack.config.js
resolve: {alias: {"react-native": "react-native-web","react": path.resolve(__dirname, "../src/react/packages/react"),"react-dom": path.resolve(__dirname, "../src/react/packages/react-dom"),"shared": path.resolve(__dirname, "../src/react/packages/shared"),"react-reconciler": path.resolve(__dirname, "../src/react/packages/react-reconciler"),"legacy-events": path.resolve(__dirname, "../src/react/packages/legacy-events"),'scheduler/tracing': path.resolve(__dirname, "../src/react/packages/scheduler/src/Tracing")}
}

修改环境变量

// 文件位置: react-test/config/env.js
const stringified = {"process.env": Object.keys(raw).reduce((env, key) => {env[key] = JSON.stringify(raw[key])return env}, {}),__DEV__: true,SharedArrayBuffer: true,spyOnDev: true,spyOnDevAndProd: true,spyOnProd: true,__PROFILE__: true,__UMD__: true,__EXPERIMENTAL__: true,__VARIANT__: true,gate: true,trustedTypes: true}

告诉 babel 在转换代码时忽略类型检查

安装：npm install @babel/plugin-transform-flow-strip-types -D
// 文件位置: react-test/config/webpack.config.js [babel-loader]
找到： loader: require.resolve('babel-loader'),
plugins: [+ require.resolve("@babel/plugin-transform-flow-strip-types"),
]

导出 HostConfig

// 文件位置: /react/packages/react-reconciler/src/ReactFiberHostConfig.js
+ export * from './forks/ReactFiberHostConfig.dom';
- invariant(false, 'This module must be shimmed by a specific renderer.');

修改 ReactSharedInternals.js 文件

// 文件位置: /react/packages/shared/ReactSharedInternals.js
- import * as React from 'react';
- const ReactSharedInternals = React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
+ import ReactSharedInternals from '../react/src/ReactSharedInternals';

关闭 eslint 扩展

// 文件位置: react/.eslingrc.js [module.exports]
// 注释 extends
- extends: [
-  'fbjs',
- 'prettier'
-]

禁止 invariant 报错

// 文件位置: /react/packages/shared/invariant.js
export default function invariant(condition, format, a, b, c, d, e, f) {
+  if (condition) return;throw new Error('Internal React error: invariant() is meant to be replaced at compile ' +'time. There is no runtime version.',);
}

在 react 源码文件夹中新建 .eslintrc.json 并添加如下配置

{"extends": "react-app","globals": {"SharedArrayBuffer": true,"spyOnDev": true,"spyOnDevAndProd": true,"spyOnProd": true,"__PROFILE__": true,"__UMD__": true,"__EXPERIMENTAL__": true,"__VARIANT__": true,"gate": true,"trustedTypes": true}
}

修改 项目中（index.js app.js）react react-dom 引入方式

import * as React from "react"
import * as ReactDOM from "react-dom"

解决 vsCode 中 flow 报错

// vscode设置
"javascript.validate.enable": false

可选项配置

// 如果你的 vscode 编辑器安装了 prettier 插件并且在保存 react 源码文件时右下角出现如下错误，按照如下步骤解决
// 全局安装 prettier
npm i prettier -g
// 配置 prettier path
Settings > Extensions > Prettier > Prettier path

解决__DEV__ 报错

删除 node_modules 文件夹，执行 npm install