JavaScript this用法

2018-06-24 02:01:27来源：未知阅读 ()

当this为全局变量时，this为window对象

<script>
    // 在全局变量中，this为window
    window.onload= function(){
        alert(window);//object window
    }
    this.onload= function(){
        alert(this);//object window
    }
</script>

当this在函数中时，this为window对象

<script>
    function xiu(kang){
        this.sear = kang;
    }
    xiu("修抗");
    alert(sear);
</script>

当this在对象中，this就为该对象（person）

<script>
    var name = "修抗";
    var person = {
        name: "user",
        xiu: function(){
            alert(this.name);
        }
    }
    person.xiu();//user
</script>

当this遇上new时，this为新创建的对象（kang）

<script>
    function Fun(){
        this.name = "修抗";
    }
    var kang = new Fun();
    alert(kang.name); //修抗
</script>

当this在内部函数中，this为window

<script>
    var name = "修抗";
    var person = {
        name : "user",
        hello : function(){
            var sayhello = function() {
                alert(this.name);
            };
            sayhello();
        }
    }
person.hello();//修抗
</script>

当this在内部函数中，如果在对象中将this作为变量保存下来，this就指向该对象

<script>
    var name = "修抗";
    var person = {
        name : "user",
        hello : function(){
            var th = this;
            var sayhello = function() {
                alert(th.name);
            };
            sayhello();
        }
    }
person.hello();//user
</script>