javascript help with variables

With some help, I wrote this javascript.

http://pastebin.com/uSSZp0j6

I don't understand how to add more than one variable to a variable, I need for there to be several "keycodes," not just one. Other than that, the script works fine.

>>28
Oh right. I knew about the prototype chain but wanted to keep it simple (i.e. not use hasOwnProperty).
Is that test meant to not feature the in operator at all? All four tests are array iteration.