new的过程做了什么，实现一个new

/**
 * 实现一个new
 * by daidai
 */
function Dog (name){
    this.name = name;
    this.say = function () {
        console.log(‘我的name叫‘ + this.name)
    }
 }

 function _new (fn,...args) {
    const _obj = Object.create(Dog.prototype)
    const rel = fn.apply(_obj,args)
    return rel instanceof Object ? rel : _obj
 }

 let news = _new(Dog,‘zhangsan‘)