JavaScript this

函数预编译过程this-window

function test(c) {
            var a = 123;

            function b() {}
            console.log(this);
        }
        test();
        //AO{
        //     arguments:[1],
        //     this:window,
        //     C:1,
        //     a:undefined,
        //     b:function(){}
        // }

全局作用域this->window

call/applay改变this指向

function Person(name,age,sex){
            this.name=name;
            this.age=age;
            this.sex=sex;
        }
        function Xiaoming(name,age,sex,weight){
            Person.call(this,name,age,sex);
            this.weight=weight;
        }
        var xiaoming = new Xiaoming("ming",1,2,180);

查看结果如下图

obj.func() func()里面的this指向obj,谁调用指向谁

 var obj = {
            a: function () {
                console.log(this.name)
            },
            name: "abc"
        }
        obj.a();