Hey you cannot use W3Schools for reference. Try Mozzila Developer Network (MDN) instead. But this is not offense, just a piece of useless comment so well. I'm not using W3Schools for reference. See W3Fools for more info and stuffs.
Ehem. Sorry for the somewhat offtopic but I really recommend you to quit searching and forking for references at W3Schools as I'm really not recommend that thing. But I will not makes myself looks like an ugly piece of cheese that just can sit down and wait for more reference - seriously I'm a creative person after all. I'm learning to be smart at coding stuffs and you know that.
But W3Schools is still good for reference yes it's still good. Yes sorry for this - I hate to tell this but yeah.
Blah sorry for the inconvenience. I'm really stating at a very bad mood now - and I'll really confused for all stuffs that I'm currently working.