~function(){
 function AutoBanner(curEleId,ajaxURL,interval){
  //把之前存储获取元素的变量都作为当前实例的私有属性
  this.banner = document.getElementById(curEleId);
  this.bannerInner = utils.firstChild(this.banner);
  this.bannerTip = utils.children(this.banner,"ul")[0];
  this.bannerLink = utils.children(this.banner,'a');
  this.bannerLeft = this.bannerLink[0];
  this.bannerRight = this.bannerLink[1];
  this.divList = this.bannerInner.getElementsByTagName('div');
  this.imgList = this.bannerInner.getElementsByTagName('img');
  this.oLis = this.bannerTip.getElementsByTagName('li');

  //之前的全局变量也应该变为自己的私有属性
  this.jsonData = null;
  this.interval = interval || 3000;
  this.autoTimer = null;
  this.step = 0;
  this.ajaxURL = ajaxURL;
  //返回当前实例
  return this.init();
 }

 AutoBanner.prototype = {
  constructor:AutoBanner,
  //Ajax请求数据
  getData:function(){
   var _this = this;
   var xhr = new XMLHttpRequest;
   xhr.open("get",this.ajaxURL + "?_="+Math.random(),false);
   xhr.onreadystatechange = function(){
    if(xhr.readyState ===4 && /^2\d{2}$/.test(xhr.status)){
     _this.jsonData = utils.formatJSON(xhr.responseText)
    }
   }
   xhr.send(null)
  },
  //实现数据绑定
  bindData:function(){
   var str = "",str2 = "";
   if(this.jsonData){
    for(var i = 0,len=this.jsonData.length;i