JavaScript如何实现淘宝商品广告效果的实例详解

ul{ margin: 0; padding: 0; } 
  li{ list-style: none; } 
 
  #ad{ width: 298px; height: 208px; border: 1px #ff6300 solid; padding: 4px 1px; text-align: center; } 
  #ad .listL{ float: left; } 
  #ad .listR{ float: right; } 
  #ad li{ width: 48px; height: 26px; border: 1px #ffadad solid; background: #fff7f7; color: #333; line-height: 26px; margin-bottom: 2px; cursor: pointer; } 
  #ad img{ height: 206px; width: 188px; background: url(images/loader_ico.gif) no-repeat center center; } 
  #ad .cur{ background: #ff8494; color: #fff }

<p id="ad"> 
  <ul class="listL"> 
   <!-- <li class="cur"></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> --> 
  </ul> 
  <a href="#"><img src="" alt=""></a> 
  <ul class="listR"> 
   <!-- <li></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> 
   <li></li> --> 
  </ul> 
 </p>

window.onload = function(){ 
  var op = document.getElementById('ad'); 
  var aUl = op.getElementsByTagName('ul'); 
  var oImg = op.getElementsByTagName('img')[0]; 
  var aImg = ['images/pic1.jpg','images/pic2.jpg','images/pic3.jpg','images/pic4.jpg','images/pic5.png','images/pic6.png','images/pic7.png','images/pic8.png','images/pic1.jpg','images/pic2.jpg','images/pic3.jpg','images/pic4.jpg','images/pic5.png','images/pic6.png']; 
  var aTxt = ['连衣裙','T恤','雪纺','铅笔裤','婚纱','外套','连体裤','包包','凉鞋','单鞋','太阳镜','丝袜','帆布鞋','情侣鞋']; 
  var len = aImg.length; 
  var oldNum = 0; 
  var num = 0; 
  var timer = null; 
  var speed = 1; 
 
  // 创建添加左右两侧li 
  for( var i = 0; i < len/2; i++){ 
   aUl[0].innerHTML += '<li>'+ aTxt[i] +'</li>' 
   aUl[1].innerHTML += '<li>'+ aTxt[i + len/2] +'</li>' 
  } 
 
  var aLiL = aUl[0].getElementsByTagName('li'); 
  var aLiR = aUl[1].getElementsByTagName('li'); 
  var arrLi = []; 
  // 将遍历的所有li添加到数组arrLi中 
  for( var i = 0; i < aLiL.length; i++){ 
   arrLi.push(aLiL[i]); 
  } 
  for( var i = 0; i < aLiR.length; i++){ 
   arrLi.push(aLiR[i]); 
  } 
  // console.log(arrLi.length); 
 
  // 函数初始化 
  function init(n){ 
   oImg.src = aImg[n]; 
   arrLi[oldNum].className = ''; 
   arrLi[n].className = 'cur'; 
   oldNum = n; 
  } 
  init(0); 
 
  // 鼠标经过li，图片切换 
  for(var i = 0; i < len; i++){ 
   arrLi[i].index = i; 
   arrLi[i].onmouseover = function(){ 
    init(this.index); 
   } 
  }; 
 
  // 定时切换 
  function fnTimer(n){ 
   timer = setInterval(function(){ 
     
    // type1:顺序切换 
    /* n ++; 
    if(n == len){ 
     n = 0; 
    }*/ 
 
    // type2：倒序切换 
    if(n == len-1){ 
     speed = -1; 
    }else if(n== 0){ 
     speed = 1; 
    } 
    n += speed; 
    init(n); 
   },1000); 
  }; 
  fnTimer(0); 
 
  // 鼠标移入，清除定时器 
  op.onmouseover = function(){ 
   clearInterval(timer); 
  }; 
 
  // 鼠标移出，开启定时器 
  op.onmouseout = function(){ 
   fnTimer(oldNum); 
  }; 
  };