话不多说，请看代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>不重复验证码</title>
<style>
.cont{width:300px;height:auto;margin:50px auto;}
#useId{width:120px;height:45px;line-height:45px;background:#ccc;text-align:center;font-size:20px;margin:10px;}
</style>
</head>
<body>
<div class="cont">
<div id="useId"></div>
<input type="text" id="txt" />
<input type="button" id="btn" value="Start" />
<div>
<script>
function $(id){
return document.getElementById(id);
}
var $useId = $('useId'),
$txt = $('txt'),
$btn = $('btn');
function getStr(){
var string = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789',
str = '';
while(str.length < 6){
var str1 = string.charAt(Math.round(Math.random() * 56));
if(str.indexOf(str1) === -1){
str += str1;
}
}
$useId.innerHTML = str;
}
function checkCode(){
if($txt.value == $useId.innerHTML){
alert('验证成功');
}else{
alert('验证失败');
}
}
$useId.onclick = getStr;
$btn.onclick = checkCode;
</script>
</body>
</html>
以上就是本文的全部内容，希望本文的内容对大家的学习或者工作能带来一定的帮助，同时也希望多多支持！