You're correct. The other comments bring up tail recursion, which would deal with this issue, but they conveniently leave out the fact that almost no JavaScript runtime actually supports it.

likewise
I always google if I don't cknow what one or enother method from others' solution means!
That's great practise!

By using the char codes? (I came up with a very similar solution)

Agreed! This is similar to other solutions but if you just made the string include the entire lower and uppercase alphabet twice, you could refactor the method to easily take in an argument about how far to rotate. :)

Nope :) However, you can use "let" instead of "var" if you want the variable to only exist in the scope of the loop.

While you are right, the "stack problem" can be dealt by adding an accumulator: GetSumHelper(a, b, acc)

For more info: http://stackoverflow.com/questions/33923/what-is-tail-recursion#37010