Text 'guesser' / tumbler like animation
Pretty fun little bit of code. Very neatly written as well. Only thing I would suggest would be to use .charAt(x) instead of using array indexers for your strings when you're comparing characters. Not a big deal but will improve compatibility among browsers and is a bit easier to read IMHO.

// Compare the two chars.
if (text.charAt(i) !== tumbleText.charAt(i))


Good stackoverflow post covers it in more detail here.