call apply bind

function foo(data){
  console.log(this,data); //this -> window
}

var obj = {name:'124'}
foo.call(obj,12) //this->obj

foo.apply(obj, [12]) //this->obj

foo.bind(obj,33)() //foo.bind(obj,33)返回函数

bind应用场景：

setTimeout(function(){
  console.log(this)
},bind(obj),1000) // this->obj