一个小的tab切换插件

1//使用 

　　var t1=new Tab({
       etype:'onmou',//默认点击触发，如果事件写错了，当作单击
       autoplay:2000,//有时间值(按照事件自动播放)和false(不自动播放)
       invoke:3,//默认是第一项。
     });

//插件的基本结构
 ;(function(){
     function Tab(options){//options：配置参数
         this.tab=document.querySelector('.tab');
         this.tabBtn=document.querySelector('.tab_btn');
         this.btns=this.tabBtn.getElementsByTagName('li');
         this.divs=this.tab.querySelectorAll('.tab_item');
         this.num=0;
         this.timer=null;
         this.options=options;
         this.settings={//默认参数
             etype:'onclick',//默认点击触发，如果事件写错了，当作单击
             autoplay:3000,//有时间值(按照事件自动播放)和false(不自动播放)
             invoke:1,//默认是第一项。
             effect:'display'//display/opacity
         }
         this.init();
     }

     Tab.prototype.init=function(){
         var that=this;
         extend(this.settings,this.options);
         if(this.settings.etype=='onclick' || this.settings.etype!='onmouseover'){
             this.tabSwitch('onclick');
         }else if(this.settings.etype=='onmouseover'){
             this.tabSwitch(this.settings.etype);
         }
         if(this.settings.autoplay){//如果配置参数传入一个时间，允许自动轮播，轮播的时间传过去
             this.autoplay(this.settings.autoplay);
         }
         if(this.settings.invoke>1 && this.settings.invoke<=this.btns.length){
             this.num=this.settings.invoke-1;
             this.tabchange();
         }
         this.tab.onmouseover=function(){
             clearInterval(that.timer);
         }
         this.tab.onmouseout=function(){
             that.autoplay(that.settings.autoplay);
         }
     }

     Tab.prototype.tabSwitch=function(e){
         var that=this;
         for(var i=0;i<this.btns.length;i++){
             this.btns[i].index=i;
             this.btns[i][e]=function(){
                 that.num=this.index;
                 that.tabchange();
             }
         }
     }
     Tab.prototype.tabchange=function(){
         for(var i=0;i<this.btns.length;i++){
             this.btns[i].className='';
             this.divs[i].className='hide';
             if(this.settings.effect=='opacity'){
                 buffermove(this.divs[i],{opacity:0});
                 this.divs[i].style.display='none';
             }
         }
         this.btns[this.num].className='active';
         if(this.settings.effect=='display' || this.settings.effect!='opacity'){
             this.divs[this.num].className='show';
         }else if(this.settings.effect=='opacity'){
             this.divs[this.num].style.display='block';
             buffermove(this.divs[this.num],{opacity:100});
         }
     }
     Tab.prototype.autoplay=function(time){
         var that=this;
         this.timer=setInterval(function(){
             that.num++;
             if(that.num>=that.btns.length){
                 that.num=0;
             }
             that.tabchange();
         },time);
     }

     function extend(obj1,obj2){
         for(var i in obj2){
             obj1[i]=obj2[i];
         }
         return obj1;
     }
     window.Tab=Tab;
 })();