1.<head>标签代码
<script type="text/javascript">
var code;
function createCode(){
code="";
var codeLength = 4;
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');
for(var i=0;i<codeLength;i++){
var index = Math.floor(Math.random()*36);
code += random[index];
}
checkCode.value = code;
}
function validate(){
var inputCode = document.getElementById("input").value.toUpperCase();
if(inputCode.length<=0){
alert("请输入验证码！");
}else if(inputCode != code){
alert("验证码输入错误!");
createCode();
document.getElementById("input").value="";
}else{
alert("合格!");
}
}
</script>
<style type="text/css">
#code{
font-family: Arial,宋体;
font-style: italic;
color: green;
border: 0;
padding: 2px 3px;
letter-spacing: 3px;
font-weight: b
}
</style>
2.<body>中代码
<body onload="createCode();">
<div>验证码：
<input type="text" id="input" />
<input type="button" id="code" onclick="createCode();" style="width:60px;" title="点击更换验证码" />
<input type="button" value="验证" onclick="validate();" />
</div>
</body>