this的构造原理实现

function User(name){
    this.name=name;

}
let lisi=new User("lisi");
console.log(lisi);//User {name: 'lisi'}
let hdcms={url:"hdcms.com"};
User.call(hdcms,"system");
console.log(hdcms);//{url: 'hdcms.com', name: 'system'}