How Can I Perform a DNS Lookup in Client-Side Javascript?

DNS Lookup in Client-Side Javascript

Performing a DNS lookup from the client's computer using client-side Javascript presents a challenge, as Javascript lacks direct access to the DNS service.

Edit: JSONP Webservice Solution

An updated solution emerged from the community: a JSONP webservice hosted on Google App Engine. This webservice returns the client's IP address. To use it:

function getip(json){
  alert(json.ip); // alerts the ip address
}
<script type="application/javascript" src="http://jsonip.appspot.com/?callback=getip"> </script>

This method eliminates the need for server proxies.

Original Answer

Prior to the JSONP solution, pure Javascript could not perform DNS lookups. However, a workaround involving a server script under the same domain was suggested. By sending an XMLHttpRequest to read the output of this server script, the IP address could be obtained.

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