Javascript load from different domain

Because of the same origin policy you can not load Javascript from a different domain. However this only applies to AJAX requests. If you add a HTML script tag to a webside the browser loads and executes it:

javascript:(s=(d=document).createElement("script")).src="http://google.de"; void(d.body.appendChild(s))

With the "javascript:" in front, you can execute it on any webpage. Just copy it in your browsers address bar and press enter. With this you can add new features to other pages. A function to delete all entries from facebooks pinboard or studivz would be nice. To make it look nice, you can add your script as bookmarklet to your browsers bookmarks.