Webpack 是一个使用比较广泛的前端项目打包工具，可以帮我们处理一些诸如 typescript、es6+、Vue、tsx 之类浏览器无法直接支持的问题，将项目打包成各个浏览器都可以直接支持的 js 文件。类似的工具还有 Vite 等。
参考资料
概念
- entry: 使用哪个模块来作为构建的起始入口。
- output: 最终打包后的文件放在哪里，以及如何命名这些文件。
- loader: 是处理文件的转换器，用于对模块源码进行转换，webpack 只能识别 js、json 文件，像 css 、ts 、jsx等文件都需要通过 loader 进行转换。
- plugin: 是一种可扩展的机制，可以打包过程中添加额外的功能。比如打包优化，资源管理，注入环境变量等。
- mode: 对于不同的环境，我们往往需要不同的配置，通过设置 mode 参数来选择环境。
项目初始化
略过 node.js 安装之类的前置步骤。
// 创建项目文件夹
mkdir start-react
// 初始化
npm init
typescript及React配置
引入 typescript及React
// react
npm add -D react react-dom
npm add -D @types/react @types/react-dom
// typescript
npm add -D typescript
// 初始化 typesript 配置，生成 tsconfig.js 文件
tsc --init
tsconfig.js 文件配置：
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Basic Options */
// "incremental": true, /* Enable incremental compilation */
"target": "ESNEXT", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
"module": "ESNext", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
// "lib": [], /* Specify library files to be included in the compilation. */
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
"jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
"sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
// "outDir": "./", /* Redirect output structure to the directory. */
"rootDir": "./src", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "tsBuildInfoFile": "./", /* Specify file to store incremental compilation information */
// "removeComments": true, /* Do not emit comments to output. */
"noEmit": true, /* Do not emit outputs. */
"importHelpers": true, /* Import emit helpers from 'tslib'. */
// "downlevelIteration": true, /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
"strict": true, /* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
"noUnusedLocals": true, /* Report errors on unused locals. */
"noUnusedParameters": true, /* Report errors on unused parameters. */
"noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
"noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
"moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
"baseUrl": "./", /* Base directory to resolve non-absolute module names. */
"paths": {
"common/*": [
"src/common/*"
],
"@/*": [
"src/*"
]
}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true, /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
/* Advanced Options */
"skipLibCheck": true, /* Skip type checking of declaration files. */
"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
},
"include": ["src"]
}
创建 src 目录，在该目录下创建文件 App.tsx 及 index.tsx，文件内容如下：
// App.tsx
import * as React from 'react'
const App: React.FC = () => {
return (
<div>
<h1>Hello lozhu!</h1>
</div>
)
}
export default App
import * as React from 'react'
import * as ReactDOM from 'react-dom/client'
import App from './App'
const root = ReactDOM.createRoot(document.getElementById('app')!)
root.render(<App />)
webpack配置
引入 webpack
npm add -D webpack webpack-cli webpack-dev-server webpack-merge
开发、生产环境配置
引入 cross-env
npm add -D cross-env
创建 scripts 文件夹及 webpack.base.js、webpack.dev.js、webpack.prod.js 文件
// webpack.base.js
const path = require('path')
module.exports = {
entry: path.resolve(__dirname, '../src/index.tsx'),
output: {
path: path.resolve(__dirname, '../dist'), // 打包后的文件存放地址
filename: '[name].[hash:8].js' // 打包的文件名
}
}
// webpack.dev.js
const { merge } = require('webpack-merge')
const base = require('./webpack.base.js')
module.exports = merge(base, {
mode: 'development',
devServer: {
open: true, // 编译完自动打开浏览器
port: 8080
}
})
// webpack.prod.js
const { merge } = require('webpack-merge')
const base = require('./webpack.base.js')
module.exports = merge(base, {
mode: 'production' // 生产模式
})
修改启动脚本
修改 package.json
{
"name": "start-react",
"version": "1.0.0",
"description": "no description",
"main": "index.js",
"scripts": {
// 启动开发环境
"dev": "cross-env NODE_ENV=development webpack serve -c scripts/webpack.dev.js",
// 生产打包
"build": "cross-env NODE_ENV=production webpack -c scripts/webpack.prod.js"
},
...
}
Babel配置
Babel 是一个 JavaScript 编译器。主要用于将高版本的JavaScript代码转为向后兼容的JS代码，从而能让我们的代码运行在更低版本的浏览器或者其他的环境中。
由于 webpack 只能识别js、json 文件， 无法识别 jsx/tsx 文件，此时如果我们尝试启动项目肯定会报错。如何让 webpack 能识别呢？此时我们就需要使用babel-loader 来转换代码，babel-loader 可以让 webpack 在构建的时候借助 Babel 对JS代码进行转译。
引入依赖
npm add -D babel-loader @babel/core @babel/preset-env @babel/preset-react @babel/preset-typescript
修改 webpack.base.js 配置
const path = require('path')
module.exports = {
entry: path.resolve(__dirname, '../src/index.tsx'),
output: {
path: path.resolve(__dirname, '../dist'), // 打包后的文件存放地址
filename: '[name].[hash:8].js' // 打包的文件名
},
resolve: {
extensions: ['.ts', '.tsx', '.mjs', '.js', '.json', '.jsx'],
alias: {
'@': path.resolve(__dirname, '../')
}
},
module: {
rules: [
{
test: /.(jsx?)|(tsx?)$/,
use: {
loader: 'babel-loader',
options: {
presets: [
['@babel/preset-env'],
['@babel/preset-typescript'],
['@babel/preset-react']
]
}
}
}
]
}
}
运行打包命令
npm run build
打包完成后，会生成 dist 目录，但是还需要 index.html 文件才能访问。
HtmlWebpackPlugin配置
可以使用 HtmlWebpackPlugin 在每次打包时自动生成 index.html 入口文件。
npm add -D html-webpack-plugin
修改 webpack.base.js 文件内容
const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
module.exports = {
entry: path.resolve(__dirname, '../src/index.tsx'),
output: {
path: path.resolve(__dirname, '../dist'), // 打包后的文件存放地址
filename: '[name].[hash:8].js' // 打包的文件名
},
resolve: {
extensions: ['.ts', '.tsx', '.mjs', '.js', '.json', '.jsx'],
alias: {
'@': path.resolve(__dirname, '../')
}
},
module: {
rules: [
{
test: /.(jsx?)|(tsx?)$/,
use: {
loader: 'babel-loader',
options: {
presets: [
['@babel/preset-env'],
['@babel/preset-typescript'],
['@babel/preset-react']
]
}
}
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: path.resolve(__dirname, '../src/index.html') // 使用自定义模板
})
]
}
在 src 目录下创建 index.html 文件
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>hello webpack</title>
</head>
<body>
<div id="app"></div>
</body>
</html>
再次运行打包命令后，dist 目录下产生了 index.html 文件，浏览器打开就能看到 App.tsx 中定义的内容。
各种loader配置
图片加载
引入依赖 url-loader 及 file-loader
npm add -D file-loader url-loader
在根目录下创建图片文件夹 assets/images，引入图片 img1.jpg 和 img2.jpg
在 App.tsx 中引入图片
import * as React from 'react'
import img1 from '../assets/images/img1.jpg'
const App: React.FC = () => {
return (
<div>
<h1>Hello lozhu!</h1>
<div>
<img src={img1} />
</div>
</div>
)
}
export default App
修改 webpack.base.js 配置
const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
module.exports = {
entry: path.resolve(__dirname, '../src/index.tsx'),
output: {
path: path.resolve(__dirname, '../dist'), // 打包后的文件存放地址
filename: '[name].[hash:8].js' // 打包的文件名
},
resolve: {
extensions: ['.ts', '.tsx', '.mjs', '.js', '.json', '.jsx'],
alias: {
'@': path.resolve(__dirname, '../')
}
},
module: {
rules: [
{
test: /.(jsx?)|(tsx?)$/,
use: {
loader: 'babel-loader',
options: {
presets: [
['@babel/preset-env'],
['@babel/preset-typescript'],
['@babel/preset-react']
]
}
}
},
{
test: /\.(jpg|png)$/,
use: [
{
loader: 'url-loader',
options: {
limit: 2000
}
}
]
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: path.resolve(__dirname, '../src/index.html') // 使用自定义模板
})
]
}
重新打包即可看到图片加载出来了:eyes:
css样式
css-loader 只能帮我们将 css 解析成 js，但不能挂载到元素上。style-loader 可以帮我们实现将样式挂载到元素上，它负责将 css 样式通过 style 标签插入到 DOM 中。通过 style-loader 实现样式挂载，自动添加 style 标签到 head 中。
使用 postcss 处理 css
npm add -D style-loader css-loader postcss postcss-loader postcss-preset-env
新建 src/assets/style/mystyle.css 样式文件
// mystyle.css
/* 标准图片样式 */
.standard-img {
width: 100px;
height: 60px;
border-radius: 8px;
}
修改 App.tsx 文件引入 css
import * as React from 'react'
import img1 from './src/assets/images/img1.jpg'
import './assets/style/mystyle.css'
const App: React.FC = () => {
return (
<div>
<h1>Hello lozhu!</h1>
<div>
<img src={img1} className="standard-img" />
</div>
</div>
)
}
export default App
修改 webpack.base.js 文件
const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
module.exports = {
entry: path.resolve(__dirname, '../src/index.tsx'),
output: {
path: path.resolve(__dirname, '../dist'), // 打包后的文件存放地址
filename: '[name].[hash:8].js' // 打包的文件名
},
resolve: {
extensions: ['.ts', '.tsx', '.mjs', '.js', '.json', '.jsx'],
alias: {
'@': path.resolve(__dirname, '../')
}
},
module: {
rules: [
{
test: /.(jsx?)|(tsx?)$/,
use: {
loader: 'babel-loader',
options: {
presets: [
['@babel/preset-env'],
['@babel/preset-typescript'],
['@babel/preset-react']
]
}
}
},
{
test: /\.(jpg|png)$/,
use: [
{
loader: 'url-loader',
options: {
limit: 2000
}
}
]
},
{
test: /\.css$/,
use: [
'style-loader',
'css-loader',
{
loader: 'postcss-loader',
options: {
postcssOptions: {
plugins: [['postcss-preset-env', {}]]
}
}
}
]
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: path.resolve(__dirname, '../src/index.html') // 使用自定义模板
})
]
}
重新打包之后可以看到图片的大小变为想要的样式了。