js验证码

实用js验证码

 

<!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>无标题页</title> 
    <style type="text/css"> 
        .code  
        {  
            background-image:url(code.jpg);  
            font-family:Arial;  
            font-style:italic;  
            color:Red;  
            border:0;  
            padding:2px 3px;  
            letter-spacing:3px;  
            font-weight:bolder;  
        }  
        .unchanged  
        {  
            border:0;  
        }  
    </style> 
    <script language="javascript" type="text/javascript"> 
      
     var code ; //在全局 定义验证码  
     function createCode()  
     {   
       code = "";  
       var codeLength = 6;//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];   
       }  
//       alert(code);  
       if(checkCode)  
       {  
         checkCode.className="code";  
         checkCode.value = code;  
       }  
         
     }  
       
      function validate ()  
     {  
       var inputCode = document.getElementById("input1").value;  
       if(inputCode.length <=0)  
       {  
           alert("请输入验证码！");
     document.loginform.input1.focus();
        return false; 
       }  
       else if(inputCode != code )  
       {  
          alert("验证码输入错误！"); 
    document.loginform.input1.focus();
       return false;
          createCode();//刷新验证码  
       }  
 
         alert("^-^ OK");
   //loginform.submit();  
  
         
       }  
         
    </script> 
</head> 
<body onload="createCode()"> 
<form name="loginform" id="loginform"  action="#"> 
     <input  type="text"   id="input1" /> 
    <input type="text" onclick="createCode()" readonly="readonly" id="checkCode" class="unchanged" style="width: 80px"  /><br /> 
    <input id="Button1"  onclick="validate();" type="button" value="确定" />   
</form> 
</body> 
</html>