javascript实现数字验证码的简单实例

时间:2020-05-13 人气:0

实例如下：

<!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);//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()*10);
       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 onload="createCode()">
<form 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>

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