一、this

當前的 關鍵字 函數(shù)的擁有者

1.函數(shù)中的引用

    var x = 1;
    function test() {
      this.x = 0;  // this==test
  };
  function test1() {
     this.x = 2;    // this ==> test1
  }
  test();
  test1();
  console.log(x)  //==> 2  從上往下按照順序執(zhí)行

2.在對象中調用

function test3(){
  return this.a;  //this,指向調用者 obj.action;
}
var obj = {}
obj.a =1;
obj.action =test3;
console.log(obj.action());  //==>1

3.構造函數(shù)

this指向實例化以后的對象

function Person(age,name) {
    this.name = name;
    this.age = age;
}
var fun = new Person('xiao1',22);
var fun2 = new Person('xiao2',22);
console.log(fun.name);

例：面試題

var number = 1;
    var object1 = {
        number:2,
        showNumber:function(){
            this.number = 3;
            (function(){
                console.log(this.number);   //==>1
            })();
            console.log(this.number);  //==>3
        }
    };
    object1.showNumber(); 

考點：函數(shù)自執(zhí)行 this指向的是window