Login script that loads the redirect site in the background

Question

I assume this is a pure javascript problem but since I am unsure I add the php tag onto it as well.

I wonder how you create a login script which is similar to facebooks login script, meaning that the site that actually logs you in is hidden and never displayed to the end user.

I want to make the redirect part hidden to the end user in this model, it should still, however, be processed by the end user's browser:

login site -> redirect -> logged in page

I would this without problems with reposts and repost questions from the browser.

TL;DR How do you create a login script similar to facebook's?

Thanks in advance

Answer 1

Try XMLHtpRequest open method

http://w3.org/TR/XMLHttpRequest/#the-open-method