Possible Duplicate:
Can I lookup the IP address of a hostname from javascript?
Can you get the IP address of the current page where the script is running?
I can get the current document’s domain using var domain = document.domain;.
In PhP you can get the IP address of a domain using the function gethostbyname($domain); is there an alternative to this function in JS?
Not that I know of.
Your best best would be using Ajax to connect to a PHP or other server-side script that does the lookup for you.