Douglas Crockford warned[1] us many years ago that mixing Javascript from multiple sources was fundamentally unsafe. The security model of the Javascript and th

Douglas Crockford warned[1] us many years ago that mixing Javascript from multiple sources was fundamentally unsafe. The security model of the Javascript and the DOM was never designed for isolation within a page. If you're including Javascript from a foreign domain in the page, you're giving them access to any data in the page (and allowing stuff like this XSS problem). In most cases, this is irresponsible. [1] https://www.youtube.com/watch?v=qfBL2sc2zUU https://www.youtube.com/watch?v=qfBL2sc2zUU (re: Google Gears stuff in that talk - remember when the talk was given)