webpack高级概念，环境变量使用(系列十一)

webapck配置目录

开发环境webpack.dev.js

const webpack = require('webpack');

const devConfig = {
    mode: 'development',
    devtool: 'cheap-module-eval-source-map',
    devServer: {
        contentBase: './dist',
        open: true,
        port: 8080,
        hot: true
    },
    module: {
        rules: [{
            test: /.scss$/,
            use: [
                'style-loader', 
                {
                    loader: 'css-loader',
                    options: {
                        importLoaders: 2
                    }
                },
                'sass-loader',
                'postcss-loader'
            ]
        }, {
            test: /.css$/,
            use: [
                'style-loader',
                'css-loader',
                'postcss-loader'
            ]
        }]
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin()
    ],
    output: {
        filename: '[name].js',
        chunkFilename: '[name].js',
    }
}

module.exports = devConfig;

生产环境，webpack.prod.js

const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");

const prodConfig = {
    mode: 'production',
    devtool: 'cheap-module-source-map',
    module: {
        rules:[{
            test: /.scss$/,
            use: [
                MiniCssExtractPlugin.loader, 
                {
                    loader: 'css-loader',
                    options: {
                        importLoaders: 2
                    }
                },
                'sass-loader',
                'postcss-loader'
            ]
        }, {
            test: /.css$/,
            use: [
                MiniCssExtractPlugin.loader,
                'css-loader',
                'postcss-loader'
            ]
        }]
    },
    optimization: {
        minimizer: [new OptimizeCSSAssetsPlugin({})]
    },
    plugins: [
        new MiniCssExtractPlugin({
            filename: '[name].css',
            chunkFilename: '[name].chunk.css'
        })
    ],
    output: {
        filename: '[name].[contenthash].js',
        chunkFilename: '[name].[contenthash].js'
    }
}

module.exports = prodConfig;

公共的webpack配置,webpack.common.js

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CleanWebpackPlugin = require('clean-webpack-plugin');
const webpack = require('webpack');
const merge = require('webpack-merge');
const devConfig = require('./webpack.dev.js');
const prodConfig = require('./webpack.prod.js');
const commonConfig = {
    entry: {
        main: './src/index.js',
    },
    module: {
        rules: [{ 
            test: /.js$/, 
            exclude: /node_modules/,
            use: [{
                loader: 'babel-loader'
            }, {
                loader: 'imports-loader?this=>window'
            }]
        }, {
            test: /.(jpg|png|gif)$/,
            use: {
                loader: 'url-loader',
                options: {
                    name: '[name]_[hash].[ext]',
                    outputPath: 'images/',
                    limit: 10240
                }
            } 
        }, {
            test: /.(eot|ttf|svg)$/,
            use: {
                loader: 'file-loader'
            } 
        }]
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: 'src/index.html'
        }), 
        new CleanWebpackPlugin(['dist'], {
            root: path.resolve(__dirname, '../')
        }),
        new webpack.ProvidePlugin({
            $: 'jquery',
            _join: ['lodash', 'join']
        }),
    ],
    optimization: {
        runtimeChunk: {
            name: 'runtime'
        },
        usedExports: true,
        splitChunks: {
      chunks: 'all',
      cacheGroups: {
          vendors: {
              test: /[\/]node_modules[\/]/,
              priority: -10,
              name: 'vendors',
          }
      }
    }
    },
    performance: false,
    output: {
        path: path.resolve(__dirname, '../dist')
    }
}

module.exports = (env) => {
    if(env && env.production) {
　　　　//合并生产的配置
        return merge(commonConfig, prodConfig);
    }else {
        return merge(commonConfig, devConfig);
    }
}

注，在公共的webpack.common.js中引入开发和生产的环境配置，在package.json中配置命令变量

  "scripts": {
    "dev-build": "webpack --config ./build/webpack.common.js",
    "dev": "webpack-dev-server --config ./build/webpack.common.js",
    "build": "webpack --env.production --config ./build/webpack.common.js"
  },

build命令，--env.production这个变量传到给webpack.common.js中的env参数，然后根据这个判断是否打包生产环境的配置还是打包开发环境的配置

此时运行， npm  run dev 或者npm run build 都是正常的。一般不采用这种方式配置

以上的配置的效果和这个文章配置效果一样的；https://www.cnblogs.com/fsg6/p/14490243.html