面向对象实例

<div id="div1">
    <input class="active" type="button" value="aaa" >
    <input type="button" value="bbb">
    <input type="button" value="ccc">
    <div style="display: block;">aaa</div>
    <div>bbb</div>
    <div>ccc</div>        
</div>

window.onload = function() {
    var oDiv = document.getElementById('div1');
    var aBtn = oDiv.getElementsByTagName('input');
    var aDiv = oDiv.getElementsByTagName('div');

    for (var i = 0; i < aBtn.length; i++) {
        aBtn[i].index = i;
        aBtn[i].onclick = function () {
            for (var i = 0; i <aBtn.length;i++) {
                aBtn[i].className='';
                aDiv[i].style.display='none';
            }
            this.className = 'active';
            aDiv[this.index].style.display='block';    
        };
    }
}

window.onload = function () {
    new TabSwitch('div1');
};

function TabSwitch(id) {
    var _this = this;
    var oDiv = document.getElementById(id);
    this.aBtn = oDiv.getElementsByTagName('input');
    aDiv = oDiv.getElementsByTagName('div');

    for (var i = 0; i < this.aBtn.length; i++) {
        this.aBtn[i].index = i;
        //this.aBtn[i].onclick=this.fnClick; //fnclick不再是函数，而是方法
        this.aBtn[i].onclick = function () {
            _this.fnClick(this); //两个this的区别 
        };
    }
}

TabSwitch.prototype.fnClick = function(oBtn) {
     //alert(this); this->aBtn,49行，fnclick被赋值给了aBtn.onclik
     //如果想要this指新new来的对象，则使用50行代码
    for (var i = 0; i <this.aBtn.length;i++) {
        this.aBtn[i].className='';
        aDiv[i].style.display='none';
    }
    oBtn.className = 'active';
    aDiv[oBtn.index].style.display='block';    
};