Check Domain Name Syntax with JS

Hello,

I would like to use JavaScript to determine the syntax validity of a domain name. This will be used in an internal Intranet, so in addition to all standard domain name extensions, other internal extensions should be allowed as well.

1. There should be at least 1 dot.
2. Only letters, numbers and dashes should be allowed before the LAST dot.
3. Only letters should be allowed AFTER the LAST dot.
4. This should be case insensitive

All of these should PASS
        www.example.com
        www.example.intranet
        sub.portal.example.intranet
        example-web-page-123.mobi
        2534457.2343.com
        234-64.23.112.intrra
        234-64.23.112.2323.5234.34323.43234.234.net


But all of these should FAIL:
        example  com
        example@example.com
        sub_portal.example.intranet
        example-web-page-123
        192.168.0.1





This does NOT work.  Any ideas how to fix it?
Thanks!

<!doctype html public "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<script>
function isValidDomain(obj){
    var urlPattern = /^(?:(?:[-a-z0-9]*[a-z0-9])?\.)+([a-z])?/;
      return urlPattern.test(obj.value);      
      }

</script>
</head>
<body>
<form name="frm1" method="post" action="" onsubmit="return ">
<input type="text" name="txt1" value="webaddress.com">
<input type="button" value="Valid Domain?" onclick="alert(isValidDomain(this.form.txt1))">
</form>
</body>
</html>
LVL 16
hankknightAsked:
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stanscott2Commented:
Use this regular expression:

/^[A-Za-z0-9\-\.]*\.[A-Za-z]*$/
0

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