Can code in a Javascript file know its own domain/URL

Question

If I have a site, example.com, and a page on that site references a Javascript at subdomain.example.com/serveAd.js -- is there a way from within serveAd.js to know its own URL, or the domain from which it was downloaded?

(The JS can certainly know all about the page that called it. I want to know if the JS knows about its own origin.)

Answer 1

You can read it from the script tag that includes it (Read the DOM).
But in what situation do you get a script you don't know from where it is?!

Answer 2

document.domain

and

window.location.hostname

should work

Answer 3

I'm pretty sure, as the script is parsed that the last <script> node available in the DOM will be the one being parsed.

Try this in an external JS to see:

var scripts = document.getElementsByTagName('script');
var lastScript = scripts[scripts.length - 1];
alert(lastScript.src);

Answer 4

If you were using jquery, you could get the full url with this kind of thing:

var fullJsUrl= $('script[src$=serveAd.js]').attr('src');

If not using jquery, it may take more work, but you get the idea ;)