<div class="wrapper" id="wrapper">
    <ul class="tab" id="tab-menu">
        <li class="tab-item active">国际大牌<span>◆</span></li>
        <li class="tab-item">国妆名牌<span>◆</span></li>
        <li class="tab-item">清洁用品<span>◆</span></li>
        <li class="tab-item">男士精品</li>
    </ul>
    <div class="products" id="tab-main">
        <div class="main selected">
            <a href="###"><img src="imgs/guojidapai.jpg" alt=""/></a>
        </div>
        <div class="main">
            <a href="###"><img src="imgs/guozhuangmingpin.jpg" alt=""/></a>
        </div>
        <div class="main">
            <a href="###"><img src="imgs/qingjieyongpin.jpg" alt=""/></a>
        </div>
        <div class="main">
            <a href="###"><img src="imgs/nanshijingpin.jpg" alt=""/></a>
        </div>
    </div>
</div>

var tb = new Tab({
        tabMenu: "tab-menu",    // 指定tab栏菜单id
        tabMain: "tab-main",    // 指定tab栏内容id
        auto: true           // 是否自动播放
    });

function Tab(obj) {
    this.tabMenus = null;
    this.tabMains = null;
    if(obj) {
        this._init(obj);
    }
}
Tab.prototype = {
    constructor: Tab,
    timer : null,
    _init:function(obj){
        this.initEle(obj);
        this.click();
        if(obj.auto){
            this.autoPlay();
        }

    },
    initEle:function(obj){
        var tabMenu = document.getElementById(obj.tabMenu);
        var tabMain = document.getElementById(obj.tabMain);
        this.tabMenus = tabMenu.children;
        this.tabMains = tabMain.children;
    },
    click: function() {
        var that = this;
        for(var i=0,len=this.tabMenus.length;i<len;i++) {
            this.tabMenus[i].onclick = function(){
                that.show(this);
                that.autoPlay(this.index);
            }
        }
    },
    show: function(currentLi) {
        for(var i=0,len=this.tabMenus.length;i<len;i++) {
            this.tabMenus[i].index = i;
            this.tabMenus[i].className = "tab-item";
            this.tabMains[i].style.display = "none";
        }
        currentLi.className += " active";
        this.tabMains[currentLi.index].style.display = "block";
    },
    autoPlay: function(currentIndex){
        var that = this;
        var index = 0;
        if(currentIndex !== undefined && currentIndex !== ""){
            index = currentIndex;
        }
        clearInterval(this.timer);
        this.timer = setInterval(function(){
            index++;
            if(index == that.tabMenus.length){
                index = 0;
            }
            that.show(that.tabMenus[index]);
        },2000);
    }
}