验证码大家应该不陌生，主要是为了网站的安全性，防止恶意注册和登陆。验证码实现的方式各有不同，下面是一段用javascript实现的验证码效果，供大家参考之用，希望能够给大家带来帮助。
运行效果图：
代码如下：
<html> <head> <title>js验证码</title> <style type="text/css"> .code { background:url(code_bg.jpg); font-family:Arial; font-style:italic; color:blue; font-size:30px; border:0; padding:2px 3px; letter-spacing:3px; font-weight:bolder; float:left; cursor:pointer; width:150px; height:60px; line-height:60px; text-align:center; vertical-align:middle; } a { text-decoration:none; font-size:12px; color:#288bc4; } a:hover { text-decoration:underline; } </style> <script type="text/javascript"> var code; function createCode() { code = ""; var codeLength = 6; //验证码的长度 var checkCode = document.getElementById("checkCode"); var codeChars = 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', '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 charNum = Math.floor(Math.random() * 52); code += codeChars[charNum]; } if(checkCode) { checkCode.className = "code"; checkCode.innerHTML = code; } } function validateCode() { var inputCode=document.getElementById("inputCode").value; if(inputCode.length <= 0) { alert("请输入验证码！"); } else if(inputCode.toUpperCase() != code.toUpperCase()) { alert("验证码输入有误！"); createCode(); } else { alert("验证码正确！"); } } </script> </head> <body> <form runat="server" onsubmit="validateCode()"> <div> <table cellspacing="5" cellpadding="5" > <tr> <td></td> <td><div ></div></td> <td><a href="#">看不清换一张</a></td> </tr> <tr> <td>验证码：</td> <td><input type="text" /></td> <td>请输入验证码</td> </tr> <tr> <td></td> <td><input type="button" value="确定" /></td> <td></td> </tr> </table> </div> </form> </body> </html>