String manipulation in IE8/IE9
str[i] where str is a string and i a valid index in the string fails and returns "undefined". Extremely strange.
String.charAt() still works fine. I've pinged Microsoft about it and they're now working on it. I am currently trying to narrow the bug even better.
Update: I just found the potential root of the bug. I am waiting for MSFT's ack to let you know. Stay tuned