~/packages/react-scripts/config/webpack.config.js 是整个 CRA 的核心。这一版本 CRA 将开发和生产的 webpack.config 合 2 为 1, 虽然精简了代码量, 但使得阅读难度大大提升
变量设置, 组件引用
const fs = require('fs')
const path = require('path')
const webpack = require('webpack')
const resolve = require('resolve')
const PnpWebpackPlugin = require('pnp-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin')
const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin')
const TerserPlugin = require('terser-webpack-plugin')
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin')
const safePostCssParser = require('postcss-safe-parser')
const ManifestPlugin = require('webpack-manifest-plugin')
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin')
const WorkboxWebpackPlugin = require('workbox-webpack-plugin')
const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin')
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin')
const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent')
const paths = require('./paths')
const getClientEnvironment = require('./env')
const ModuleNotFoundPlugin = require('react-dev-utils/ModuleNotFoundPlugin')
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin-alt')
const typescriptFormatter = require('react-dev-utils/typescriptFormatter')
const getCacheIdentifier = require('react-dev-utils/getCacheIdentifier')
// 通过 GENERATE_SOURCEMAP=false 控制是否生成 sourcemap
const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false'
// 通过 INLINE_RUNTIME_CHUNK=false 控制是否内联 runtimeChunk
const shouldInlineRuntimeChunk = process.env.INLINE_RUNTIME_CHUNK !== 'false'
// Check if TypeScript is setup
const useTypeScript = fs.existsSync(paths.appTsConfig)
// 样式文件正则
const cssRegex = /\.css$/
const cssModuleRegex = /\.module\.css$/
const sassRegex = /\.(scss|sass)$/
const sassModuleRegex = /\.module\.(scss|sass)$/CRA 中 webpack.config.js 配置说明说的很完善, 我只会添加一些个人见解和简单翻译
module.exports = function(webpackEnv) {
const isEnvDevelopment = webpackEnv === 'development'
const isEnvProduction = webpackEnv === 'production'
// webpack 使用 `publicPath` 来决定app部署在哪
// 它要求以 斜杠'/' 开始, 否则生成的asset无法正确部署
// 在开发模式, 我们总是以 根目录'/'开始
const publicPath = isEnvProduction
? paths.servedPath
: isEnvDevelopment && '/'
// 有一些 app 不使用 客服端渲染
// 所以 通过设置 homepage: "." 可以使用相对路径
const shouldUseRelativeAssetPaths = publicPath === './'
// `publicUrl` 和 `publicPath` 类似, 但是 `publicUrl`是 `publicPath`去掉最后的 /
const publicUrl = isEnvProduction
? publicPath.slice(0, -1)
: isEnvDevelopment && ''
// 获取需要 inject的 环境变量
const env = getClientEnvironment(publicUrl)
// 获取style loader的通用方法
const getStyleLoaders = (cssOptions, preProcessor) => {
const loaders = [
isEnvDevelopment && require.resolve('style-loader'),
isEnvProduction && {
loader: MiniCssExtractPlugin.loader,
options: Object.assign(
{},
shouldUseRelativeAssetPaths ? { publicPath: '../../' } : undefined
),
},
{
loader: require.resolve('css-loader'),
options: cssOptions,
},
{
// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
loader: require.resolve('postcss-loader'),
options: {
// Necessary for external CSS imports to work
// https://github.com/facebook/create-react-app/issues/2677
ident: 'postcss',
plugins: () => [
require('postcss-flexbugs-fixes'),
require('postcss-preset-env')({
autoprefixer: {
flexbox: 'no-2009',
},
stage: 3,
}),
],
sourceMap: isEnvProduction && shouldUseSourceMap,
},
},
].filter(Boolean)
if (preProcessor) {
loaders.push({
loader: require.resolve(preProcessor),
options: {
sourceMap: isEnvProduction && shouldUseSourceMap,
},
})
}
return loaders
}
return {
mode: isEnvProduction ? 'production' : isEnvDevelopment && 'development',
// Stop compilation early in production
bail: isEnvProduction,
// 开发环境, 是使用 cheap-module-source-map
// 生产, 基于 shouldUseSourceMap 判断是否使用 'source-map'
// 备注: 我对 cheap-module-source-map 这种sourcemap不喜欢, 有不少bug。
devtool: isEnvProduction
? shouldUseSourceMap
? 'source-map'
: false
: isEnvDevelopment && 'cheap-module-source-map',
entry: [
// CRA 定制了和服务器端和客户端通信的组件, react-dev-utils/webpackHotDevClient
// 记住, WebpackDevServer 是服务器, react-dev-utils/webpackHotDevClient 是于页面通信的客户端
isEnvDevelopment &&
require.resolve('react-dev-utils/webpackHotDevClient'),
// 项目根目录
paths.appIndexJs,
].filter(Boolean),
output: {
// 构建目录, 如果在开发环境, 那么会使用 cache 方式, 不会实际输入到disk中
path: isEnvProduction ? paths.appBuild : undefined,
// Add /* filename */ comments to generated require()s in the output.
pathinfo: isEnvDevelopment,
// 设置生成文件的名称
// 开发模式下, 不产生真实文件
filename: isEnvProduction
? 'static/js/[name].[chunkhash:8].js'
: isEnvDevelopment && 'static/js/bundle.js',
// 设置chunk文件的名称
chunkFilename: isEnvProduction
? 'static/js/[name].[chunkhash:8].chunk.js'
: isEnvDevelopment && 'static/js/[name].chunk.js',
// 生产模式根据外部情况改变.
// 开发模式使用 "/.
publicPath: publicPath,
devtoolModuleFilenameTemplate: isEnvProduction
? info =>
path
.relative(paths.appSrc, info.absoluteResourcePath)
.replace(/\\/g, '/')
: isEnvDevelopment &&
(info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/')),
},
optimization: {
//只在生产模式下有用，如何压缩代码
minimize: isEnvProduction,
minimizer: [
new TerserPlugin({
terserOptions: {
parse: {
ecma: 8,
},
compress: {
ecma: 5,
warnings: false,
comparisons: false,
inline: 2,
},
mangle: {
safari10: true,
},
output: {
ecma: 5,
comments: false,
ascii_only: true,
},
},
parallel: true,
cache: true,
sourceMap: shouldUseSourceMap,
}),
// This is only used in production mode
new OptimizeCSSAssetsPlugin({
cssProcessorOptions: {
parser: safePostCssParser,
map: shouldUseSourceMap
? {
//使得css输出成文件
inline: false,
annotation: true,
}
: false,
},
}),
],
// webpack v4 代码分割 split vendor and commons
// https://twitter.com/wSokra/status/969633336732905474
// https://medium.com/webpack/webpack-4-code-splitting-chunk-graph-and-the-splitchunks-optimization-be739a861366
splitChunks: {
chunks: 'all',
name: false,
},
// 是否生成 runtimeCache
runtimeChunk: true,
},
resolve: {
// This allows you to set a fallback for where Webpack should look for modules.
// We placed these paths second because we want `node_modules` to "win"
// if there are any conflicts. This matches Node resolution mechanism.
// https://github.com/facebook/create-react-app/issues/253
modules: ['node_modules'].concat(
// It is guaranteed to exist because we tweak it in `env.js`
process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
),
// 设置后缀, 即 import * from "./button", 可以省略后缀
extensions: paths.moduleFileExtensions
.map(ext => `.${ext}`)
.filter(ext => useTypeScript || !ext.includes('ts')),
alias: {
// react-native浏览器端渲染
'react-native': 'react-native-web',
},
plugins: [
// 支持 yarn 的 Plug'n'Play 特性
// Adds support for installing with Plug'n'Play, leading to faster installs and adding
// guards against forgotten dependencies and such.
PnpWebpackPlugin,
// 只允许开发者调用 src目录下的文件
new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
],
},
resolveLoader: {
plugins: [
// 支持 yarn 的 Plug'n'Play 特性
// Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
// from the current package.
PnpWebpackPlugin.moduleLoader(module),
],
},
module: {
strictExportPresence: true,
rules: [
// 禁用 require.ensure as it's not a standard language feature.
{ parser: { requireEnsure: false } },
// eslint
{
test: /\.(js|mjs|jsx)$/,
// eslint 配置必须前置
enforce: 'pre',
use: [
{
options: {
formatter: require.resolve('react-dev-utils/eslintFormatter'),
eslintPath: require.resolve('eslint'),
// @remove-on-eject-begin
baseConfig: {
extends: [require.resolve('eslint-config-react-app')],
settings: { react: { version: '999.999.999' } },
},
ignore: false,
useEslintrc: false,
// @remove-on-eject-end
},
loader: require.resolve('eslint-loader'),
},
],
include: paths.appSrc,
},
{
// 使用 oneOf 可以按照顺序执行，如果都不满足, 执行最后的 file loader
oneOf: [
// "url" loader works like "file" loader except that it embeds assets
// smaller than specified limit in bytes as data URLs to avoid requests.
// A missing `test` is equivalent to a match.
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve('url-loader'),
options: {
limit: 10000,
name: 'static/media/[name].[hash:8].[ext]',
},
},
// Process application JS with Babel.
// The preset includes JSX, Flow, TypeScript, and some ESnext features.
{
test: /\.(js|mjs|jsx|ts|tsx)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
customize: require.resolve(
'babel-preset-react-app/webpack-overrides'
),
babelrc: false,
configFile: false,
// CRA 自定义了 babel配置, 独立成了一个模块 babel-preset-react-app
presets: [require.resolve('babel-preset-react-app')],
// Make sure we have a unique cache identifier, erring on the
// side of caution.
// We remove this when the user ejects because the default
// is sane and uses Babel options. Instead of options, we use
// the react-scripts and babel-preset-react-app versions.
cacheIdentifier: getCacheIdentifier(
isEnvProduction
? 'production'
: isEnvDevelopment && 'development',
[
'babel-plugin-named-asset-import',
'babel-preset-react-app',
'react-dev-utils',
'react-scripts',
]
),
plugins: [
[
require.resolve('babel-plugin-named-asset-import'),
{
loaderMap: {
svg: {
ReactComponent:
'@svgr/webpack?-prettier,-svgo![path]',
},
},
},
],
],
cacheDirectory: true,
cacheCompression: isEnvProduction,
compact: isEnvProduction,
},
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
// CRA 依然还会处理 node_modules以外的模块
{
test: /\.(js|mjs)$/,
exclude: /@babel(?:\/|\\{1,2})runtime/,
loader: require.resolve('babel-loader'),
options: {
babelrc: false,
configFile: false,
compact: false,
// CRA 自定义了 babel配置, 独立成了一个模块 babel-preset-react-app
presets: [
[
require.resolve('babel-preset-react-app/dependencies'),
{ helpers: true },
],
],
cacheDirectory: true,
cacheCompression: isEnvProduction,
cacheIdentifier: getCacheIdentifier(
isEnvProduction
? 'production'
: isEnvDevelopment && 'development',
[
'babel-plugin-named-asset-import',
'babel-preset-react-app',
'react-dev-utils',
'react-scripts',
]
),
// If an error happens in a package, it's possible to be
// because it was compiled. Thus, we don't want the browser
// debugger to show the original code. Instead, the code
// being evaluated would be much more helpful.
sourceMaps: false,
},
},
// "postcss" loader applies autoprefixer to our CSS.
// "css" loader resolves paths in CSS and adds assets as dependencies.
// "style" loader turns CSS into JS modules that inject <style> tags.
// In production, we use MiniCSSExtractPlugin to extract that CSS
// to a file, but in development "style" loader enables hot editing
// of CSS.
// By default we support CSS Modules with the extension .module.css
// 一系类的css模块处理
{
test: cssRegex,
exclude: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction && shouldUseSourceMap,
}),
sideEffects: true,
},
// Adds support for CSS Modules (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction && shouldUseSourceMap,
modules: true,
getLocalIdent: getCSSModuleLocalIdent,
}),
},
// Opt-in support for SASS (using .scss or .sass extensions).
// By default we support SASS Modules with the
// extensions .module.scss or .module.sass
{
test: sassRegex,
exclude: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
sourceMap: isEnvProduction && shouldUseSourceMap,
},
'sass-loader'
),
// Don't consider CSS imports dead code even if the
// containing package claims to have no side effects.
// Remove this when webpack adds a warning or an error for this.
// See https://github.com/webpack/webpack/issues/6571
sideEffects: true,
},
// Adds support for CSS Modules, but using SASS
// using the extension .module.scss or .module.sass
{
test: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
sourceMap: isEnvProduction && shouldUseSourceMap,
modules: true,
getLocalIdent: getCSSModuleLocalIdent,
},
'sass-loader'
),
},
// "file" loader makes sure those assets get served by WebpackDevServer.
// When you `import` an asset, you get its (virtual) filename.
// In production, they would get copied to the `build` folder.
// This loader doesn't use a "test" so it will catch all modules
// that fall through the other loaders.
{
loader: require.resolve('file-loader'),
// Exclude `js` files to keep "css" loader working as it injects
// its runtime that would otherwise be processed through "file" loader.
// Also exclude `html` and `json` extensions so they get processed
// by webpacks internal loaders.
exclude: [/\.(js|mjs|jsx|ts|tsx)$/, /\.html$/, /\.json$/],
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
},
// ** STOP ** Are you adding a new loader?
// Make sure to add the new loader(s) before the "file" loader.
],
},
],
},
plugins: [
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin(
Object.assign(
{},
{
inject: true,
template: paths.appHtml,
},
isEnvProduction
? {
minify: {
removeComments: true,
collapseWhitespace: true,
removeRedundantAttributes: true,
useShortDoctype: true,
removeEmptyAttributes: true,
removeStyleLinkTypeAttributes: true,
keepClosingSlash: true,
minifyJS: true,
minifyCSS: true,
minifyURLs: true,
},
}
: undefined
)
),
// Inlines the webpack runtime script. This script is too small to warrant
// a network request.
isEnvProduction &&
shouldInlineRuntimeChunk &&
new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime~.+[.]js/]),
// Makes some environment variables available in index.html.
// The public URL is available as %PUBLIC_URL% in index.html, e.g.:
// <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
// In production, it will be an empty string unless you specify "homepage"
// in `package.json`, in which case it will be the pathname of that URL.
// In development, this will be an empty string.
// 这个插件使得所有env变量在html可以使用
new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw),
// This gives some necessary context to module not found errors, such as
// the requesting resource.
new ModuleNotFoundPlugin(paths.appPath),
// Makes some environment variables available to the JS code, for example:
// if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
// It is absolutely essential that NODE_ENV is set to production
// during a production build.
// Otherwise React will be compiled in the very slow development mode.
new webpack.DefinePlugin(env.stringified),
// This is necessary to emit hot updates (currently CSS only):
isEnvDevelopment && new webpack.HotModuleReplacementPlugin(),
// Watcher doesn't work well if you mistype casing in a path so we use
// a plugin that prints an error when you attempt to do this.
// See https://github.com/facebook/create-react-app/issues/240
isEnvDevelopment && new CaseSensitivePathsPlugin(),
// If you require a missing module and then `npm install` it, you still have
// to restart the development server for Webpack to discover it. This plugin
// makes the discovery automatic so you don't have to restart.
// See https://github.com/facebook/create-react-app/issues/186
isEnvDevelopment &&
new WatchMissingNodeModulesPlugin(paths.appNodeModules),
isEnvProduction &&
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: 'static/css/[name].[contenthash:8].css',
chunkFilename: 'static/css/[name].[contenthash:8].chunk.css',
}),
// Generate a manifest file which contains a mapping of all asset filenames
// to their corresponding output file so that tools can pick it up without
// having to parse `index.html`.
new ManifestPlugin({
fileName: 'asset-manifest.json',
publicPath: publicPath,
}),
// Moment.js is an extremely popular library that bundles large locale files
// by default due to how Webpack interprets its code. This is a practical
// solution that requires the user to opt into importing specific locales.
// https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
// You can remove this if you don't use Moment.js:
new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
// Generate a service worker script that will precache, and keep up to date,
// the HTML & assets that are part of the Webpack build.
// workbox 用于离线app, 是否必须开启, 我抱有怀疑
isEnvProduction &&
new WorkboxWebpackPlugin.GenerateSW({
clientsClaim: true,
exclude: [/\.map$/, /asset-manifest\.json$/],
importWorkboxFrom: 'cdn',
navigateFallback: publicUrl + '/index.html',
navigateFallbackBlacklist: [
// Exclude URLs starting with /_, as they're likely an API call
new RegExp('^/_'),
// Exclude URLs containing a dot, as they're likely a resource in
// public/ and not a SPA route
new RegExp('/[^/]+\\.[^/]+$'),
],
}),
// TypeScript type checking
useTypeScript &&
new ForkTsCheckerWebpackPlugin({
typescript: resolve.sync('typescript', {
basedir: paths.appNodeModules,
}),
async: false,
checkSyntacticErrors: true,
tsconfig: paths.appTsConfig,
compilerOptions: {
module: 'esnext',
moduleResolution: 'node',
resolveJsonModule: true,
isolatedModules: true,
noEmit: true,
jsx: 'preserve',
},
reportFiles: [
'**',
'!**/*.json',
'!**/__tests__/**',
'!**/?(*.)(spec|test).*',
'!**/src/setupProxy.*',
'!**/src/setupTests.*',
],
watch: paths.appSrc,
silent: true,
formatter: typescriptFormatter,
}),
].filter(Boolean),
// Some libraries import Node modules but don't use them in the browser.
// Tell Webpack to provide empty mocks for them so importing them works.
node: {
dgram: 'empty',
fs: 'empty',
net: 'empty',
tls: 'empty',
child_process: 'empty',
},
// Turn off performance processing because we utilize
// our own hints via the FileSizeReporter
performance: false,
}
}这篇webpack配置可以算是webpack的经典配置, 包含大量的插件使用, 非常适合收藏