Web制作验证码功能实例代码

<div class="centent-" style=""> 
   <div class="centent-left"><span></span>验证码</div> 
   <input type="text" class="verification-code-input"> 
   <div class="verification-code"><img id="yzm" src="/SchoolRoll/auser/code/check"></div> 
   <div class="change"><span>看不清？</span><span style="color:#37CAF2;cursor: pointer;" id="changeImgCode">换一张</span></div> 
  </div> 

var yzm =document.getElementById("yzm"); 
 var changeImgCode =document.getElementById("changeImgCode"); 
 yzm.onclick=function () { 
  changPin(); 
 } 
 changeImgCode.onclick=function () { 
  changPin(); 
 } 
 // 换验证码 
 function changPin() { 
  $("#yzm").attr("src", "/SchoolRoll/auser/code/check?time=" + Math.random()); 
 }