// JScript 文件

    var code ; //在全局 定义验证码   
     function createCode(checkCode)   
     {    
       code = "";   
       var codeLength = 4;//验证码的长度   
       var checkCode = document.getElementById("checkCode");   
       var selectChar = new Array(0,1,2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');//所有候选组成验证码的字符，当然也可以用中文的   
           
       for(var i=0;i<codeLength;i++)   
       {  
          var charIndex = Math.floor(Math.random()*36);   
          code +=selectChar[charIndex]; 
       }   
       if(checkCode)   
       {   
         checkCode.className="code";   
         checkCode.value = code; 
       }   
     }