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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>idCode</title>
<style>
.code{
font-family:Arial;
font-style:italic;
color:red;
border:0;
padding:2px 3px;
letter-spacing:3px;
font-weight:bold;
background: yellow;
opacity: 0.8;
}
#checkCode{
width: 60px;
text-align: center;
}
</style>
</head>
<form action="#">
<input type="text" id="inValue">
<input type="text" readonly="readonly" id="checkCode" class="code">
<br>
<br>
<input id="btn" type="button" value="确定">
</form>
<script>
window.onload = function(){
createCode();
var checkCode = document.getElementById_x_x_x("checkCode");
var btn = document.getElementById_x_x_x("btn");
checkCode.onclick = function(){
createCode();
}
btn.onclick = function(){
validate();
}
}
var code;//在全局定义验证码
function createCode(){
code = "";//code存储字符串
var codeLength = 4;//验证码的长度
var selectChar = [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
var getRandomColor = function(){
return ‘#‘+(Math.random()*0xffffff<<0).toString(16);
}//随机生成背景颜色
for(var i=0; i < codeLength; i ++)
{
var charIndex = Math.floor(Math.random()*62);
//alert(charIndex);
code += selectChar[charIndex];
}
//alert(code);
if(checkCode)
{
checkCode.style.background = getRandomColor();
checkCode.value = code;
}
}
function validate(){
var inputCode = document. getElementById("inValue").value;
if(inputCode.length<=0)
{
alert("请输入验证码！");
}
else if(inputCode.toUpperCase()!=code.toUpperCase())
{
alert("验证码输入错误！");
createCode();//刷新验证码
}
else
{
alert("输入正确，验证成功");
}
}
</script>
</body>
</html>
js验证码
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原文地址：http://www.cnblogs.com/gyx19930120/p/4419980.html
