防止重复的两种配置方法

1.配置dependOn

const path = require('path');

 module.exports = {
   mode: 'development',
   entry: {
    index: {
      import: './src/index.js',
      dependOn: 'shared',
    },
    another: {
      import: './src/another-module.js',
      dependOn: 'shared',
    },
    shared: 'lodash',
   },
   output: {
     filename: '[name].bundle.js',
     path: path.resolve(__dirname, 'dist'),
   },
   optimization: {
    runtimeChunk: 'single',
  },
 };

可以看到dist目录下生成的文件，index.bundle.js和another.bundle.js以来的lodash被分离出来到shared.bundle.js
配置：

   optimization: {
    runtimeChunk: 'single',
  },

会有runtime.bundle.js生成，官网的解释是为了避免这里的麻烦

2.SplitChunksPlugin插件

const path = require('path');

  module.exports = {
    mode: 'development',
    entry: {
      index: './src/index.js',
      another: './src/another-module.js',
    },
    output: {
      filename: '[name].bundle.js',
      path: path.resolve(__dirname, 'dist'),
    },
   optimization: {
     splitChunks: {
       chunks: 'all',
     },
   },
  };

dist目录下会生成如下文件，lodash被分离到vendors-node_modules_lodash_lodash_js.bundle.js文件中