巧用数组制作图片切换js代码

<!DOCTYPE html> 

<html lang="en"> 
<head> 
 <meta charset="UTF-8"> 
 <title>图片切换</title> 
 <style> 
 .box{ 
 width: 600px; 
 height:400px; 
 border: 10px solid #ccc; 
 position: relative; 
 margin: 40px auto 0; 
 } 
 .box a{ 
 width: 30px; 
 height: 30px; 
 background-color: #000; 
 border: 5px solid #fff; 
 position: absolute; 
 top:180px; 
 text-align: center; 
 font-size:25px; 
 font-weight: bold; 
 line-height: 30px; 
 color:#fff; 
 text-decoration: none; 
 filter: alpha(opacity:40); 
 opacity: 0.4; 
 } 
 .box a:hover{ 
 filter:alpha(opacity:80); 
 opacity:0.8; 
 } 
 .box #prev{ 
 left: 10px; 
 } 
 .box #next{ 
 right: 10px; 
 } 
 #text,#num{ 
 height: 30px; 
 line-height:30px; 
 width: 600px; 
 color:#fff; 
 position: absolute; 
 left: 0; 
 background-color: #000; 
 text-align: center; 
 filter: alpha(opacity:80); 
 opacity: 0.8; 
 margin:0; 
 } 
 .box #text{ 
 bottom: 0; 
 } 
 .box #num{ 
 top:0; 
 } 
 .box #img1{ 
 width: 600px; 
 height: 400px; 
 } 
 </style> 
 <script> 
 window.onload = function () { 
 var oPrev = document.getElementById("prev"); 
 var oNext = document.getElementById("next"); 
 var oText = document.getElementById("text"); 
 var oNum = document.getElementById("num"); 
 var oImg = document.getElementById("img1"); 
 
 var arrUrl = ['images/1.jpg','images/2.jpg','images/3.jpg','images/4.jpg']; 
 var arrText = ['文字1','文字2','文字3','文字4']; 
 
 //初始化 
 var num = 0; 
 function fnTab(){ 
 oNum.innerHTML = num + 1 + '/' + arrText.length; 
 oImg.src = arrUrl[num]; 
 oText.innerHTML = arrText[num]; 
 }; 
 fnTab(); 
 oPrev.onclick = function(){ 
 num --; 
 if( num == -1){ 
  num = arrUrl.length -1; 
 } 
 fnTab(); 
 }; 
 oNext.onclick = function(){ 
 num ++; 
 if(num == arrUrl.length){ 
  num = 0; 
 } 
 fnTab(); 
 }; 
 }; 
 </script> 
</head> 
<body> 
 <div class="box"> 
 <a id="prev" href="javascript:;"> < </a> 
 <a id="next" href="javascript:;"> > </a> 
 <p id="text">图片正在加载中……</p> 
 <span id="num">数量正在统计中……</span> 
 <img id="img1" src="../images/1.jpg" alt=""> 
 </div> 
</body> 
</html>