A cheat sheet for JavaScript lookahead and lookbehind regular expressions.
Topic: JavaScript – Page 11
HTML input elements hold references to their labels if there are any
The relatedTarget event property gives information about the previous/next element when dealing with focus events.
If the 2nd argument of String.prototype.replace is a string replacement patterns can create hard to find bugs
The omission of the error argument in try/catch JavaScript expressions is now supported in mayor browsers.