there are now two entry files

--src
 |--- a.js 
 |--- b.js     

a.js

class Test{
    constructor(){
        this.a = 123;
    }
    show = ()=>{
        console.log(this.a)
    }
}
export default new Test();

b.js

import "./a"

webapck.config

{
    entry:{
        a:"./src/a.js"
        b:"./src/b.js"
    }
}

I want to introduce polyfill into an entry file (a may also introduce other modules) or use es2015 to convert to es5
while b entry file remains the original output, then the output es6 code does not have polyfill.

has anyone ever tried this way