musical transposition in javascript

I'm trying to make a transposer in JavaScript..
Give it a key and a scale/mode and it will generate it for you
For instance
C Lydian (WWWHWWH) is C D E F# G A B
C Aeolian (WHWWHWW) is C D Eb F G Ab Bb
I cannot for the life of me figure out how to accomplish this.
Thoughts?
>inb4 SICP

>>22
Put it this way, if you need an integer you use an integer. You do not use "1", this much is obvious to any newbie coder. Yet the corollary, that when you need a collection of integers, you use a collection of integers seems less obvious to you? The one integer solution was even worse, as you would need to use binary operations to get the number out instead of whatever string->integer function javascript provides.