<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<input type="text" id="textCode" />
<label class="myLabel">码：
<input type = "button" id="code" onclick="createCode()" style="border: 0;background-color: transparent;padding: 0;"/>
</label>
<div id="btn" style=" 50px; height: 30px; text-align: center; line-height: 30px; border: 1px solid red;">验证</div>
</body>
</html>
<script type="text/javascript" src="js/jquery-1.10.2.min.js" ></script>
<script type="text/javascript">
// 图形验证码
var code ; //在全局定义验证码
//产生验证码
window.onload = function createCode(){
code = "";
var codeLength = 4;//验证码的长度
var checkCode = document.getElementById("code");
var random = 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');//随机数
for(var i = 0; i < codeLength; i++) {//循环操作
var index = Math.floor(Math.random()*36);//取得随机数的索引（0~35）
code += random[index];//根据索引取得随机数加到code上
}
checkCode.value = code;//把code值赋给验证码
}
$("#btn").click(function(){
if($("#textCode").val() == $("#code").val()){
alert("正确");
}else{
alert("错误");
}
});
</script>