javascript实现数字+字母验证码的简单实例


<!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>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
    <title>js验证码</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 = 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','wW','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!");  
       }  
       else if(inputCode != code )  
       {  
          alert("验证码输入错误!");  
          createCode();//刷新验证码  
       }  
       else  
       {  
         alert("OK");  
       }  

       }  

    </script> 
</head> 
<body> 
<form  action="#"> 
     <input  type="text"   /> 
    <input type="text" readonly="readonly"  /><br /> 
    <input  type="button" value="确定" />   
</form> 
</body> 
</html>

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