function Parent(firstName,color){    this.firstName = firstName;    this.color = color;    this.showName = function (){        console.log("我家姓氏:"+this.firstName);    }}Parent.prototype.showAll=function(){    console.log("姓:"+this.firstName+"\n"+"喜愛的顏色:"+this.color);}function Child(myName,age,firstName,color){    this.myName = myName;    this.age = age;     Child.prototype=Parent.prototype;    Parent.call(this,firstName,color);}/*Child.prototype=Parent.prototype;*/var c = new Child("帥",23,"孫","粉色");var d=new Parent("孫","粉色");d.showAll();//姓:孫            //喜愛的顏色:粉色c.showAll();//error c.showAll is not a functioncall對象冒充為什么this不能獲得構造函數Parent的原型？還有Child.prototype=Parent.prototype;寫在Child函數里不行，為什么拿出來寫在window環境就可以？