webpack 基本配置

基本配置，主要包含：

• 拆分配置和 merge
• 启动本地服务
• 处理 ES6
• 处理样式
• 处理图片
• （模块化）

公共配置文件 webpack.common.js

const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const { srcPath, distPath } = require('./paths')
module.exports = {
    entry: path.join(srcPath, 'index'),
    module: {
        rules: [
            {
                // 处理 ES6 等
                test: /\.js$/,
                loader: ['babel-loader'],
                include: srcPath,
                exclude: /node_modules/
            },
            // {
            //     test: /\.vue$/,
            //     loader: ['vue-loader'],
            //     include: srcPath
            // },
            // {
            //     test: /\.css$/,
            //     // loader 的执行顺序是：从后往前（知识点）
            //     loader: ['style-loader', 'css-loader']
            // },
            {
                test: /\.css$/,
                // loader 的执行顺序是：从后往前
                loader: ['style-loader', 'css-loader', 'postcss-loader'] // 加了 postcss
            },
            {
                test: /\.less$/,
                // 增加 'less-loader' ，注意顺序
                loader: ['style-loader', 'css-loader', 'less-loader']
            }
        ]
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: path.join(srcPath, 'index.html'),
            filename: 'index.html'
        })
    ]
}

开发环境配置 webpack.dev.js

const path = require('path')
const webpack = require('webpack')
const webpackCommonConf = require('./webpack.common.js')
const { smart } = require('webpack-merge')
const { srcPath, distPath } = require('./paths')
module.exports = smart(webpackCommonConf, {
    mode: 'development',
    module: {
        rules: [
            // 直接引入图片 url
            {
                test: /\.(png|jpg|jpeg|gif)$/,
                use: 'file-loader'
            }
        ]
    },
    plugins: [
        new webpack.DefinePlugin({
            // window.ENV = 'development'
            ENV: JSON.stringify('development')
        })
    ],
    devServer: {
        port: 8080,
        progress: true,  // 显示打包的进度条
        contentBase: distPath,  // 根目录
        open: true,  // 自动打开浏览器
        compress: true,  // 启动 gzip 压缩
        // 设置代理
        proxy: {
            // 将本地 /api/xxx 代理到 localhost:3000/api/xxx
            '/api': 'http://localhost:3000',
            // 将本地 /api2/xxx 代理到 localhost:3000/xxx
            '/api2': {
                target: 'http://localhost:3000',
                pathRewrite: {
                    '/api2': ''
                }
            }
        }
    }
})

生成环境配置 webpack.prod.js

const path = require('path')
const webpack = require('webpack')
const { CleanWebpackPlugin } = require('clean-webpack-plugin')
const webpackCommonConf = require('./webpack.common.js')
const { smart } = require('webpack-merge')
const { srcPath, distPath } = require('./paths')
module.exports = smart(webpackCommonConf, {
    mode: 'production',
    output: {
        filename: 'bundle.[contentHash:8].js',  // 打包代码时，加上 hash 戳
        path: distPath,
        // publicPath: 'http://cdn.abc.com'  // 修改所有静态文件 url 的前缀（如 cdn 域名），这里暂时用不到
    },
    module: {
        rules: [
            // 图片 - 考虑 base64 编码的情况
            {
                test: /\.(png|jpg|jpeg|gif)$/,
                use: {
                    loader: 'url-loader',
                    options: {
                        // 小于 5kb 的图片用 base64 格式产出
                        // 否则，依然延用 file-loader 的形式，产出 url 格式
                        limit: 5 * 1024,
                        // 打包到 img 目录下
                        outputPath: '/img1/',
                        // 设置图片的 cdn 地址（也可以统一在外面的 output 中设置，那将作用于所有静态资源）
                        // publicPath: 'http://cdn.abc.com'
                    }
                }
            },
        ]
    },
    plugins: [
        new CleanWebpackPlugin(), // 会默认清空 output.path 文件夹
        new webpack.DefinePlugin({
            // window.ENV = 'production'
            ENV: JSON.stringify('production')
        })
    ]
})

配置文件还引入了一个 paths.js 的文件

const path = require('path')
const srcPath = path.join(__dirname, '..', 'src')
const distPath = path.join(__dirname, '..', 'dist')
module.exports = {
    srcPath,
    distPath
}

想要使用 babel 功能，还需要在根目录增加 .babelrc 文件

{
    "presets": ["@babel/preset-env"],
    "plugins": []
}

当处理 css 时，为了保持兼容性，自动前缀，引入 postcss-loader 模块启用 autoprefixer 功能，在根目录新增 postcss.config.js 文件

module.exports = {
    plugins: [require('autoprefixer')]
}

最后，看下完整的 package.json 配置

{
  "name": "webpack-demo",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "devBuild": "webpack --config build-base-conf/webpack.dev.js",
    "dev": "webpack-dev-server --config build-base-conf/webpack.dev.js",
    "build": "webpack --config build-base-conf/webpack.prod.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.7.4",
    "@babel/preset-env": "^7.7.4",
    "autoprefixer": "^9.7.3",
    "babel-loader": "^8.0.6",
    "clean-webpack-plugin": "^3.0.0",
    "css-loader": "^3.2.1",
    "file-loader": "^5.0.2",
    "happypack": "^5.0.1",
    "html-webpack-plugin": "^3.2.0",
    "less": "^3.10.3",
    "less-loader": "^5.0.0",
    "mini-css-extract-plugin": "^0.8.0",
    "optimize-css-assets-webpack-plugin": "^5.0.3",
    "postcss-loader": "^3.0.0",
    "style-loader": "^1.0.1",
    "terser-webpack-plugin": "^2.2.2",
    "url-loader": "^3.0.0",
    "webpack": "^4.41.2",
    "webpack-cli": "^3.3.10",
    "webpack-dev-server": "^3.9.0",
    "webpack-merge": "^4.2.2",
    "webpack-parallel-uglify-plugin": "^1.1.2"
  },
  "dependencies": {
    "lodash": "^4.17.15",
    "moment": "^2.24.0"
  }
}