一、前言
最近遇到了不少ts/tsx => js的webpack配置问题，所以想简单聊一聊。 一般react项目我们都会用create-react-app模版来搭建，该模版默认是js来写的，根据官方指引转成tsx之后，因为我们会用到一些第三方库（ui库，css module等），抛出的问题无法在create-scripts或craco这种包装层上处理，需要eject之后再处理。
二、问题
我在yarn run eject得到webpack暴露出来的配置文件之后，跑yarn start启动dev服务非常的慢，然后我找了可能存在的原因（比如引入了不必要的包、引入了不该引用的less文件 => 因为我这是微前端服务项目，在编译主项目的同时也会同时编译从子项目中export的内容），最后排除了一些因素，最后发现是antd没有按需引入，在启动dev服务的时候打包/编译花费的时间太长，百度了一圈，发现都是零零散散的信息，并没有一个全面的问题分析（大多都是paste©），正好最近我在对babel关于ts编译为js的presets/plugins的相关知识了解之后，终于发现了一些有用信息。
三、解决
如果你的项目是create-react-app是用js/jsx写的，只需要：
- 安装babel-plugin-import
yarn babel-plugin-import --save-dev
- 添加配置到babel-loader的plugins（插个搭建项目的建议，开发人员得清晰的记住项目的构建过程，因为你在修改了一些配置之后，就会产生一些不好解决或者说不可逆的问题） 比如create-react-app+antd of react旧版本推荐用babel-plugin-import+customize的方法改写ui库的默认样式，而现在又是推荐用craco来处理，这些五花八门的改写命令其实问题很多，如果在外层改写，craco的简洁的官网和网上零散的信息往往会让人无从下手，加大了各种复杂度！
下面我贴下前后代码，还有打包对比：
// webpack.config.js before
module: {
strictExportPresence: true,
rules: [
// Disable require.ensure as it's not a standard language feature.
{ parser: { requireEnsure: false } },
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
// TODO: Merge this config once `image/avif` is in the mime-db
// https://github.com/jshttp/mime-db
{
test: [/\.avif$/],
loader: require.resolve('url-loader'),
options: {
limit: imageInlineSizeLimit,
mimetype: 'image/avif',
name: 'static/media/[name].[hash:8].[ext]',
},
},
// "url" loader works like "file" loader except that it embeds assets
// smaller than specified limit in bytes as data URLs to avoid requests.
// A missing `test` is equivalent to a match.
{
test: /\.tsx?$/,
loader: 'awesome-typescript-loader',
},
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve('url-loader'),
options: {
limit: imageInlineSizeLimit,
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)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
customize: require.resolve('babel-preset-react-app/webpack-overrides'),
presets: [
[
require.resolve('babel-preset-react-app'),
{
runtime: hasJsxRuntime ? 'automatic' : 'classic',
},
],
],
plugins: [
[
require.resolve('babel-plugin-named-asset-import'),
{
loaderMap: {
svg: {
ReactComponent: '@svgr/webpack?-svgo,+titleProp,+ref![path]',
},
},
},
],
isEnvDevelopment && shouldUseReactRefresh && require.resolve('react-refresh/babel'),
].filter(Boolean),
// This is a feature of `babel-loader` for webpack (not Babel itself).
// It enables caching results in ./node_modules/.cache/babel-loader/
// directory for faster rebuilds.
cacheDirectory: true,
// See #6846 for context on why cacheCompression is disabled
cacheCompression: false,
compact: isEnvProduction,
},
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
{
test: /\.(js|mjs)$/,
exclude: /@babel(?:\/|\\{1,2})runtime/,
loader: require.resolve('babel-loader'),
options: {
babelrc: false,
configFile: false,
compact: false,
presets: [[require.resolve('babel-preset-react-app/dependencies'), { helpers: true }]],
plugins: [
// [
// '@babel/plugin-transform-react-jsx',
// {
// throwIfNamespace: false, // defaults to true
// runtime: 'automatic', // defaults to classic
// },
// ],
// '@babel/plugin-transform-typescript',
],
cacheDirectory: true,
// See #6846 for context on why cacheCompression is disabled
cacheCompression: false,
// Babel sourcemaps are needed for debugging into node_modules
// code. Without the options below, debuggers like VSCode
// show incorrect code and set breakpoints on the wrong lines.
sourceMaps: shouldUseSourceMap,
inputSourceMap: shouldUseSourceMap,
},
},
// "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
{
test: cssRegex,
exclude: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
}),
// 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 (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
modules: {
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: 3,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
},
'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: 3,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
modules: {
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$/],
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
},
// ** STOP ** Are you adding a new loader?
// Make sure to add the new loader(s) before the "file" loader.
],
},
],
},
module: {
strictExportPresence: true,
rules: [
// Disable require.ensure as it's not a standard language feature.
{ parser: { requireEnsure: false } },
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
// TODO: Merge this config once `image/avif` is in the mime-db
// https://github.com/jshttp/mime-db
{
test: [/\.avif$/],
loader: require.resolve('url-loader'),
options: {
limit: imageInlineSizeLimit,
mimetype: 'image/avif',
name: 'static/media/[name].[hash:8].[ext]',
},
},
// "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: imageInlineSizeLimit,
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)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
customize: require.resolve('babel-preset-react-app/webpack-overrides'),
presets: [
[
require.resolve('babel-preset-react-app'),
{
runtime: hasJsxRuntime ? 'automatic' : 'classic',
},
],
],
plugins: [
[
require.resolve('babel-plugin-named-asset-import'),
{
loaderMap: {
svg: {
ReactComponent: '@svgr/webpack?-svgo,+titleProp,+ref![path]',
},
},
},
],
isEnvDevelopment && shouldUseReactRefresh && require.resolve('react-refresh/babel'),
[
'import',
{
libraryName: 'antd',
style: true, // support less
},
],
].filter(Boolean),
// This is a feature of `babel-loader` for webpack (not Babel itself).
// It enables caching results in ./node_modules/.cache/babel-loader/
// directory for faster rebuilds.
cacheDirectory: true,
// See #6846 for context on why cacheCompression is disabled
cacheCompression: false,
compact: isEnvProduction,
},
},
{
test: /\.tsx?$/,
loader: 'awesome-typescript-loader',
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
{
test: /\.(js|mjs)$/,
exclude: /@babel(?:\/|\\{1,2})runtime/,
loader: require.resolve('babel-loader'),
options: {
babelrc: false,
configFile: false,
compact: false,
presets: [[require.resolve('babel-preset-react-app/dependencies'), { helpers: true }]],
plugins: [
// [
// '@babel/plugin-transform-react-jsx',
// {
// throwIfNamespace: false, // defaults to true
// runtime: 'automatic', // defaults to classic
// },
// ],
// '@babel/plugin-transform-typescript',
],
cacheDirectory: true,
// See #6846 for context on why cacheCompression is disabled
cacheCompression: false,
// Babel sourcemaps are needed for debugging into node_modules
// code. Without the options below, debuggers like VSCode
// show incorrect code and set breakpoints on the wrong lines.
sourceMaps: shouldUseSourceMap,
inputSourceMap: shouldUseSourceMap,
},
},
// "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
{
test: cssRegex,
exclude: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
}),
// 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 (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
modules: {
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: 3,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
},
'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: 3,
sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
modules: {
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.
],
},
],
},
这里做了两处处理：一是将awesome-typescript-loader置于babel-loader之后，二是添加了babel-plugin-import的默认配置到plugins中。
由上可以看到0.chuk.js这个包的体积减去了部分，不仅减少了很多dev启动编译的时间，也在后续打包中减少打包体积！
三、结束语
从html => html5 => js => es6 => ts => esnext这个前端发展过程中产生的问题，真的是各种各样，以前只需要对cmd、amd写法编译为js，现在又需要对ts转js做各种处理，中间还有jsx/tsx...，各种loader、presets交替更新，只有不停的适应。。
