JavaScript关键字this的用法总结

alert(this);  // 显示 [object Window]
alert(this === window);  // 显示 true

<input type="button" value="点击这里显示this" onclick="alert(this)" />
<!-- 显示 [object htmlInputElement] -->

<input id="demo" type="button" value="点击这里显示this" />
<script type="text/javascript">
document.getElementById("demo").onclick = function(){
    alert(this);  // 显示 [object HTMLInputElement]
}
</script>

var user = "xiaoming";
function ItXueyuan(user){
    this.name = "IT学院";
    this.domain = "www.itxueyuan.org";
    this.user = user;
    this.showUser = function(){
      alert(this.user);
    }
}
var zhangsan = new ItXueyuan("zhangsan");
zhangsan.showUser();  // 显示"zhangsan"

var wangming = new ItXueyuan("wangming");
wangming.showUser();  // 显示 wangming