创建vendor chunk 和多入口公用的common chunk 。
共有三个入口_pageA, pageB, pageC 。_这三个入口公用一些模块，以下配置会把至少有两个入口公用的模块单独打包，同时node_modules里的模块也单独打包。

webpack.config.js

var path = require("path");
module.exports = {
    // mode: "development" || "production",
    entry: {
        pageA: "./pageA",
        pageB: "./pageB",
        pageC: "./pageC"
    },
    optimization: {
        chunkIds: "named",
        splitChunks: {
            cacheGroups: {
                commons: {
                    chunks: "initial",
                    minChunks: 2,
                    maxInitialRequests: 5, // The default limit is too small to showcase the effect
                    minSize: 0 // This is example is too small to create commons chunks
                },
                vendor: {
                    test: /node_modules/,
                    chunks: "initial",
                    name: "vendor",
                    priority: 10,
                    enforce: true
                }
            }
        }
    },
    output: {
        path: path.join(__dirname, "dist"),
        filename: "[name].js"
    }
};

pageA.js

var vendor1 = require('vendor1');
var utility1 = require('./utility1');
var utility2 = require('./utility2');
module.exports = "pageA";

pageB.js

var vendor2 = require('vendor2');
var utility2 = require('./utility2');
var utility3 = require('./utility3');
module.exports = "pageB";

pageC.js

var utility2 = require('./utility2');
var utility3 = require('./utility3');
module.exports = "pageC";

依赖关系：

• pageA
  • utility1
  • utility2
• pageB
  • utility2
  • utility3
• pageC
  • utility2
  • utility3

打包后的文件

• vendor
  • vendor1
  • vendor2
• common
  • utility2
  • utility3
• pageA
  • pageA
  • utility1
• pageB
  • pageB
• pageC
  • pageC