随机数Math对象下的random方法，源码如下，可以直接使用。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title></title> <style type="text/css"> .de{ width:450px; height:450px; border:4px solid #ccc; margin:0 auto; margin-top:50px;} .we{ width:450px; height:450px;} </style> <script type="text/javascript"> function de() { var we = document.getElementById("we"); var img = ["XMJ.jpg", "XMJX.jpg", "psb.jpg"]; //url 链接数组 var allNumber = img.length; // 保存img的个数 var randomImg = parseInt(allNumber * Math.random()); //Math.random随机数 we.setAttribute("src",img[randomImg]); } window.onload = function () { de(); } </script> </head> <body> <div class="de"> <img src="psb.jpg" alt="" title="" class="we" id="we" /> </div> </body> </html>