简单的前端验证码

 1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 2 <html xmlns="http://www.w3.org/1999/xhtml" >
 3 <head>
 4     <title>验证码Demo</title>
 5     <meta charset="UTF-8">
 6     <style type="text/css">
 7         .code {font-family:Arial;font-style:italic;color:Red;border:0;padding:2px 3px;letter-spacing:3px;font-weight:bolder;}
 8         .unchanged{border:0;}
 9     </style>
10     <script type="text/javascript">
11         var code;//在全局 定义验证码
12         function createCode(){
13             code = "";
14             var codeLength = 6;//验证码的长度
15             var checkCode = document.getElementById("checkCode");
16             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
17             for(var i=0;i < codeLength;i++){
18                 var charIndex = Math.floor(Math.random()*36);
19                 code +=selectChar[charIndex];
20             }
21             //alert(code);
22             if(checkCode){
23                 checkCode.className="code";
24                 checkCode.value = code;
25             }
26         }
27         function validate(){
28             var inputCode = document.getElementById("input1").value;
29             if(inputCode.length <= 0){
30                 alert("请输入验证码!");
31             }else if(inputCode != code){
32                 alert("验证码输入错误!");
33                 createCode();//刷新验证码
34             }else{
35                 alert("^-^ OK");
36             }
37         }
38     </script>
39 </head>
40 <body onload="createCode()">
41 <form  action="#">
42     <input type="text" id="input1" />
43     <input type="text" onclick="createCode()" readonly="readonly" id="checkCode" class="unchanged" style="80px"/><br/>
44     <input id="Button1" onclick="validate();" type="button" value="确定" />
45 </form>
46 </body>
47 </html>
原文地址:https://www.cnblogs.com/liubeimeng/p/5089143.html