this指向,call apply bind

一,this指向

①普通函数调用,this指向window

function fn(){
  console.log(this)  //window 
}
fn();

②构造函数调用,this指向实例对象

function Person(age,name){
  this.age=age;
  this.name=name;
  console.log(this)   //Person {age:10,name:'abc'}    此处this指向Person的实例对象p1
}
var p1=new Person(10,'abc')

③对象方法调用,this指向该方法所属的对象

var obj={
  fn:function(){console.log(this)  //obj
  }
}
obj.fn();