There is an experimental full-screen API, but it's not consistent between browsers:
http://caniuse.com/#feat=fullscreen[
^]
There's a project on GitHub which attempts to hide these changes behind a consistent API:
https://github.com/sindresorhus/screenfull.js/[
^]
However, this API will
NOT allow you to enter full-screen mode without user interaction, and it will
NOT prevent the user from exiting full-screen mode. And that's a
good thing. If a random website was able to take over your entire screen, and prevent you from accessing anything else on your computer, that would be a major security problem.