原型链

function Fddm（person,count）｛
       this.person = person;
       this.count = count;
｝
Fddm.prototype = {
        constructor:Fddm        //用=相当于替换原来的prototypetype对象，原对象的constructor便不在了，所以要手动添加

        sing:function(){
              console.log(‘i like sing’)
         }
        talking:function(){
              console.log(‘i like talking’)
         }

}
var wxy = new Fddm(‘王心怡’,2)

console.log(wxy.protoFddm.prototype) //true
console.log(Fddm.prototype.constructorFddm) //true
console.log(Fddm.proto==Object.prototype) //true
console.log(Object.proto==null) //true