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简单的验证码登录功能的实现
<html>
<head>
<style>
#code{
font-family:Arial;
font-style:italic;
font-weight:bold;
border:0;
letter-spacing:2px;
color:blue;
}
</style>
<script>
//生成验证码的JS
var code;
function createCode(){
//生成验证码
code = '';
//设置验证码的长度为4
var codeLength = 4;
var codeV = document.getElementById('code');
//随机函数生成验证码
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');
for(var i = 0; i < codeLength; i++){
//取得随机数的索引（0-35）
var index = Math.floor(Math.random()*36);
//根据索引取得随机数加到code上
code += random[index];
}
//把code值赋给验证码
codeV.value = code;
}
//校验验证码
function validate(){
var oValue = document.getElementById('input').value.toUpperCase();
if(oValue ==0){
alert('请输入验证码');
}else if(oValue != code){
alert('验证码输入有误');
document.getElementByID('input').value="";//清空文本框
oValue = ' ';
//重新生成验证码
createCode();
}else{
alert("验证码正确");2018/4/4
}
}
//加载页面的同生成验证码并显示
window.onload = function (){
createCode();
}
</script>
</head>
<body>
<div>
<input type = "text" id = "input" value="" />
<input type = "button" id="code" onclick="createCode()"/>
<input type = "button" value = "验证" onclick = "validate()"/>
</div>
</body>
</html>