原型链

a.sayName() 里面的this指向是，谁调用这个方法，this就指向谁

Person.prototype={ name:"a", sayName:function(){ console.log(this.name); } } function Person (){ this.name="b"; } var person=new Person(); person.sayName(); //b Person.prototype={ height:100 } function Person(){ this.eat=function(){ this.height++; } } var person=new Person(); person.eat(); person.height //101 person._proto_.height //100

object.create()

// var obj=Object.create(原型) // var obj={name:"sunny",age:123}; // var obj1=Object.create(obj); Person.prototype.name="sunny"; function Person(){ } var person=Object.create(Person.prototype);

绝大多数对象的最终都会继承自Object.prototype

var object=Object.create(null); obj._proto_={name:"sunny"} obj.name //underfined

toString()

var num=123; num.toString(); //”123“ true.toString(); //"true" obj.toString(); //[object Object]

重写

Object.prototype.toString=function(){ } Peron.prototype={ } function Person(){ toString:function(){ return "hehe"; } } var person=new Person(); person.toString(); //"hehe"