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<head>
<title><a href='http://js.zz5u.net'><u>JavaScript</u></a>用正则验证IP地址格式是否正确_网页代码站(www.6a8a.com)</title>
</head>
<body>
<script language="javascript">
function f_check_IP()
{ var ip = document.getElementById('reg_ip').value;
var re=/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/;//正则表达式
if(re.test(ip))
{
if( RegExp.$1<256 && RegExp.$2<256 && RegExp.$3<256 && RegExp.$4<256)
return true;
}
alert("IP有误！");
return false;
}
</script>
<form method="post" action="" onsubmit="return f_check_IP()">
您的IP：<input type="text" id="reg_ip" name="reg_ip">
<input type="submit" name="submit" value="提交">
</form>
<br />
</body>
</html>