"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "webpack-dev-server --config ./config/webpack.dev.js",
    "build": "webpack --config ./config/webpack.pro.js"
},
"devDependencies": {
    "@babel/core": "^7.7.7",
    "@babel/plugin-transform-runtime": "^7.7.6",
    "@babel/preset-env": "^7.7.7",
    "@babel/runtime": "^7.7.7",
    "autoprefixer": "^9.7.3",
    "babel-loader": "^8.0.6",
    "clean-webpack-plugin": "^3.0.0",
    "css-loader": "^3.4.0",
    "file-loader": "^5.0.2",
    "html-webpack-plugin": "^3.2.0",
    "less": "^3.10.3",
    "less-loader": "^5.0.0",
    "mini-css-extract-plugin": "^0.9.0",
    "postcss-loader": "^3.0.0",
    "style-loader": "^1.1.2",
    "url-loader": "^3.0.0",
    "webpack": "^4.41.5",
    "webpack-cli": "^3.3.10",
    "webpack-dev-server": "^3.10.1",
    "webpack-merge": "^4.2.2"
},
"dependencies": {
    "@babel/polyfill": "^7.7.0"
}

// webpack.base.js
const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const { CleanWebpackPlugin } = require('clean-webpack-plugin')

module.exports = {
    entry: {
        index: './src/js/index.js'
    },
    output: {
        path: path.resolve(__dirname, '../dist'),
        filename: '[name].js'
    },
    module: {
        rules: [
            {
                test: /\.(jpe?g|png|gif)$/,
                use: {
                    loader: 'url-loader',
                    options: {
                        name: '[name].[ext]',
                        outputPath: 'images/',
                        limit: 2048,
                    }
                }
            },
            {
                test: /.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: [
                            [
                                '@babel/preset-env',
                                // {
                                //     targets: {
                                //         edge: '17',
                                //         firefox: '60',
                                //         chrome: '67',
                                //         safari: '11.1'
                                //     },
                                //     useBuiltIns: 'usage', // 按需加载 
                                //     // 会污染全局环境, 开发组件库的话 推荐闭包方式  @babel/plugin-transform-runtime
                                // }
                            ]
                        ],
                        plugins: ['@babel/plugin-transform-runtime']
                    }
                }
            }
        ]
    },
    plugins: [
        new HtmlWebpackPlugin({
            title: '首页',
            template: './src/pages/index.html',
            inject: true,
            chunks: ['index'],
            filename: 'index.html'
        }),
        new CleanWebpackPlugin(),
    ]
}

// webpack.dev.js
const webpack = require('webpack')
const merge = require('webpack-merge')

const baseConfig = require('./webpack.base')

const devConfig = {
    mode: 'development',
    devtool: 'cheap-module-eval-source-map',
    devServer: {
        port: 8081,
        open: true,
        hotOnly: true, // 即使 HMR不生效,不自动刷新
    },
    module: {
        rules: [{
            test: /\.less$/,
            use: ['style-loader', 'css-loader', 'less-loader', {
                loader: 'postcss-loader',
                options: {
                    plugins: () => [
                        require('autoprefixer')({
                            overrideBrowserslist: ['last 2 versions', '>1%']
                        })
                    ]
                }
            }]
        }, ]
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin() // 模板化更新
    ]
}

module.exports = merge(baseConfig, devConfig)

// webpack.pro.js
const path = require('path')
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const merge = require('webpack-merge')

const baseConfig = require('./webpack.base')

const proConfig = {
    mode: 'production',
    output: { // 输出文件
        path: path.resolve(__dirname, '../dist'),
        filename: '[name]_[chunkhash:8].js'
    },
    devtool: 'none', // 线上推荐不开启
    module: {
        rules: [{
            test: /\.less$/,
            use: [MiniCssExtractPlugin.loader, 'css-loader', 'less-loader', {
                loader: 'postcss-loader',
                options: {
                    plugins: () => [
                        require('autoprefixer')({
                            overrideBrowserslist: ['last 2 versions', '>1%']
                        })
                    ]
                }
            }]
        }, ]
    },
    plugins: [
        new MiniCssExtractPlugin({ // css 分离成文件
            filename: "[name]_[contenthash:8].css"
        }),
    ]
}

module.exports = merge(baseConfig, proConfig)

在改变 number.js 中的值时, 只有此处会刷新.

// index.js
import number from './number'
number()  

if(module.hot) {
    module.hot.accept('./number', function() {
        document.body.removeChild(document.getElementById('number'))
        number()
    })  
}

// number.js
function number() {
    var div = document.createElement('div')
    div.setAttribute('id', 'number')
    div.innerHTML = 100
    document.body.appendChild(div)
}

export default number;

如果只想统一配置的话请查看上一篇: webpack的简单配置