公共程式碼提取功能是針對多入口檔案的；

　　背景：在pageA.js和pageB.js中分別引用subPageA.js和subPageB.js

　　webpack.config.js檔案：

 1 var path = require('path')
 2 module.exports = {
 3     entry:{
 4         pageA:'./src/pageA.js',
 5         pageB:'./src/pageB.js'
 6     },
 7     output: {
 8         filename: "[name].js",
 9         path:path.resolve(__dirname,'./dist')
 
10     },
11     optimization: {
12         splitChunks:{
13             cacheGroups: {
14                 vender:{
15                     test:/node_modules/,
16                     chunks:'initial',
17                     name:'vender',
18                     priority:10
19                 },
20                 utils:{
 
21                     chunks:'initial',
22                     name:'utils',
23                     minSize:0
24                 }
25             }
26         }
27     }
28 }