function Banner(width, height) {/*类*/
  /*以下最外层div*/
  var that = this;
  this.width = width;
  this.height = height;
  this.oBox = document.getElementById("box");
  this.oBox.style.width = width;
  this.oBox.style.height = height;
  this.oBox.style.margin = "0 auto";
  this.oBox.style.overflow = "hidden";
  this.oBox.style.position = "relative";
  /*以下轮播区的div*/
  this.oBoxInner = this.oBox.getElementsByTagName('div')[0];
  this.oBoxInner.style.height = height;
  this.oBoxInner.style.position = "absolute";
  this.oBoxInner.style.left = 0;
  this.oBoxInner.style.right = 0;
  this.aDiv = this.oBoxInner.getElementsByTagName('div');//单个轮播图
  this.oBoxInner.innerHTML/* 轮播区的内部后面*/ += this.aDiv[0].outerHTML/*第一个轮播图片的外部*/;
  this.oBoxInner.style.width = parseFloat(width) * this.aDiv.length + "px";//轮播区的宽度
  for (var i = 0; i < this.aDiv.length; i++) {/*遍历轮播区的每个div及其内部的图片*/
    this.aDiv[i].style.width = width;
    this.aDiv[i].style.height = height;
    this.aDiv[i].style.float = "left";
    this.aDiv[i].aImg = this.aDiv[i].getElementsByTagName('img')[0];
    this.aDiv[i].aImg.style.width = "100%";
    this.aDiv[i].aImg.style.height = "100%";
  }
  /*以下是焦点区部分（定位在轮播区的右下方）*/
  var oUl=document.createElement('ul');
  for(i=0; i';
  }
  this.oBox.appendChild(oUl);
  this.oUl = this.oBox.getElementsByTagName('ul')[0];
  this.oUl.style.position = "absolute";
  this.oUl.style.right = "10px";
  this.oUl.style.bottom = "10px";
  this.aLi = this.oUl.getElementsByTagName('li');
  for (i = 0; i < this.aLi.length; i++) {/*遍历焦点区的每个焦点*/
    this.aLi[i].style.width = "18px";
    this.aLi[i].style.height = "18px";
    this.aLi[i].style.float = "left";
    this.aLi[i].style.listStyle = "none";
    this.aLi[i].style.background = "green";
    this.aLi[i].style.borderRadius = "50%";
    this.aLi[i].style.marginLeft = "10px";
    this.aLi[i].style.cursor = "pointer";
  }
  /*以下是向左向右两个箭头式按钮*/
  for(i=0; i<2; i++){
    var oA=document.createElement('a');
    oA.href="javascript:;" rel="external nofollow" 
    this.oBox.appendChild(oA);
  }
  /*以下是左按钮（点击它，图片向左运动）*/
  this.oBtnL = this.oBox.getElementsByTagName('a')[0];
  this.oBtnL.style.width = "30px";
  this.oBtnL.style.height = "30px";
  this.oBtnL.style.position = "absolute";
  this.oBtnL.style.top = (parseFloat(this.height) / 2 - 15) + "px";
  this.oBtnL.style.left = "30px";
  this.oBtnL.style.border = "10px solid red";
  this.oBtnL.style.borderLeft = "none";
  this.oBtnL.style.borderBottom = "none";
  this.oBtnL.style.opacity = "0.3";
  this.oBtnL.style.filter = "alpha(opacity=30)";
  this.oBtnL.style.display = "none";
  this.oBtnL.style.transform = "rotate(-135deg)";
  this.oBtnL.onclick = function () {
    if (that.step <= 0) {
      that.step = that.aDiv.length - 1;
      that.css(that.oBoxInner, 'left', -that.step * parseFloat(that.width));
    }
    that.step--;
    that.animate(that.oBoxInner, {left: -that.step * parseFloat(that.width)});
    that.bannerTip();
  };
  /*以下是右按钮（点击它，图片向右运动）*/
  this.oBtnR = this.oBox.getElementsByTagName('a')[1];
  this.oBtnR.style.width = "30px";
  this.oBtnR.style.height = "30px";
  this.oBtnR.style.position = "absolute";
  this.oBtnR.style.top = (parseFloat(this.height) / 2 - 15) + "px";
  this.oBtnR.style.right = "30px";
  this.oBtnR.style.border = "10px solid red";
  this.oBtnR.style.borderLeft = "none";
  this.oBtnR.style.borderBottom = "none";
  this.oBtnR.style.opacity = "0.3";
  this.oBtnR.style.filter = "alpha(opacity=30)";
  this.oBtnR.style.display = "none";
  this.oBtnR.style.transform = "rotate(45deg)";
  this.oBtnR.onclick = function () {
    if (that.step >= that.aDiv.length - 1) {
      that.step = 0;
      that.css(that.oBoxInner, 'left', 0)
    }
    that.step++;
    that.animate(that.oBoxInner, {left: -that.step * parseFloat(that.width)}, 1000);
    that.bannerTip();
  };
  /*以下是其它*/
  this.step = 0;//记录每次运动
  this.timer = null;//定时器
  this.init();//初始化轮播图
}
Banner.prototype = {//类的原型
  constructor: Banner,
  /*getCss：获取元素的属性值*/
  getCss: function (curEle, attr) {
    var val = null;
    var reg = null;
    if (getComputedStyle) {//标准浏览器
      val = getComputedStyle(curEle, false)[attr];
    } else {//非标准浏览器
      if (attr === 'opacity') {
        val = curEle.currentStyle.filter; //'alpha(opacity=10)'
        reg = /^alpha\(opacity[=:](\d+)\)$/i;
        return reg.test(val) ? reg.exec(val)[1] / 100 : 1;
      }
      val = curEle.currentStyle[attr];
    }
    reg = /^[+-]?((\d|([1-9]\d+))(\.\d+)?)(px|pt|rem|em)$/i;
    return reg.test(val) ? parseInt(val) : val;
  },
  /*setCss：设置元素的属性值*/
  setCss: function (curEle, attr, value) {
    if (attr === 'float') {
      curEle.style.cssFloat = value;
      curEle.style.styleFloat = value;
      return;
    }
    if (attr === 'opacity') {
      curEle.style.opacity = value;
      curEle.style.filter = 'alpha(opacity=' + (value * 100) + ')';
      return;
    }
    var reg = /^(width|height|top|right|bottom|left|((margin|padding)(top|right|bottom|left)?))$/i;
    if (reg.test(attr)) {
      if (!(value === 'auto' || value.toString().indexOf('%') !== -1)) {
        value = parseFloat(value) + 'px';
      }
    }
    curEle.style[attr] = value;
  },
  /*setGroupCss：设置元素的一组属性值*/
  setGroupCss: function (curEle, options) {
    if (options.toString() !== '[object Object]') return;
    for (var attr in options) {
      this.setCss(curEle, attr, options[attr]);
    }
  },
  /*css：getCss、setCss、setGroupCss的合写*/
  css: function () {
    if (typeof arguments[1] === 'string') {
      if (typeof arguments[2] === 'undefined') {
        return this.getCss(arguments[0], arguments[1]);//当第三个参数不存在，是获取；
      } else {
        this.setCss(arguments[0], arguments[1], arguments[2]);//当第三个参数存在时，是设置；
      }
    }
    if (arguments[1].toString() === '[object Object]') {
      this.setGroupCss(arguments[0], arguments[1]);//设置元素的一组属性值
    }
  },
  /*animate：轮播图动画函数*/
  animate: function (curEle, target, duration) {
    /*1.定义动画的运行轨迹*/
    function tmpEffect(t, b, c, d) {
      return b + c / d * t;//开始时的位置+总变化/总时间*已经过去的时间
    }
    /*2.为公式的每个参数做准备*/
    var begin = {};
    var change = {};
    for (var attr in target) {
      begin[attr] = this.css(curEle, attr);
      change[attr] = target[attr] - begin[attr];
    }
    duration = duration || 700;
    var time = 0;
    var that = this;
    /*3.开启一个定时器，让时间不断累加；根据时间和公式，求出最新的位置；*/
    clearInterval(curEle.timer); //开起一个定时器前，先关闭没用的定时器
    curEle.timer = setInterval(function () {
      time += 10;
      /*4.定时器停止运动的条件（time>=duration）*/
      if (time >= duration) {
        that.css(curEle, target);
        clearInterval(curEle.timer);
        return;
      }
      /*5.拿到每个属性的最新值，并且赋值给元素对应的属性；*/
      for (var attr in target) {
        var curPos = tmpEffect(time, begin[attr], change[attr], duration);
        that.css(curEle, attr, curPos);
      }
    }, 10)
  },
  /*初始化轮播图*/
  init: function () {
    var _this = this;
    /*1.开启自动轮播*/
    this.timer = setInterval(function () {
      _this.autoMove();
    }, 2000);
    /*2.开启焦点，每个焦点与每张轮播图对应*/
    this.bannerTip();
    /*3.鼠标移入轮播区，轮播暂停；鼠标移出轮播区，轮播恢复*/
    this.over_out();
    /*4.点击焦点，响应对应的轮播图片*/
    this.handleChange();
  },
  handleChange: function () {
    for (var i = 0; i < this.aLi.length; i++) {
      this.aLi[i].index = i;
      var that = this;
      this.aLi[i].onclick = function () {
        that.step = this.index;
        that.animate(that.oBoxInner, {left: -that.step * parseFloat(that.width)});
        that.bannerTip();
      }
    }
  },
  autoMove: function () {
    if (this.step >= this.aDiv.length - 1) {
      this.step = 0;
      this.css(this.oBoxInner, 'left', 0)
    }
    this.step++;
    this.animate(this.oBoxInner, {left: -this.step * parseFloat(this.width)}, 1000);
    this.bannerTip();
  },
  bannerTip: function () {
    var tmpStep = this.step >= this.aLi.length ? 0 : this.step;
    for (var i = 0; i < this.aLi.length; i++) {
      this.aLi[i].className = i === tmpStep ? 'on' : null;
      if (this.aLi[i].className === "on") {
        this.aLi[i].style.background = "red";
      } else {
        this.aLi[i].style.background = "green";
      }
    }
  },
  over_out: function () {
    var _this = this;
    _this.oBox.onmouseover = function () {
      clearInterval(_this.timer);
      _this.oBtnL.style.display = 'block';
      _this.oBtnR.style.display = 'block';
    };
    _this.oBox.onmouseout = function () {
      _this.timer = setInterval(function () {
        _this.autoMove()
      }, 2000);
      _this.oBtnL.style.display = 'none';
      _this.oBtnR.style.display = 'none';
    }
  }
};