Lookbehind

[ShimShamSam]

Any chance of getting negative/positive lookbehind implemented? This might be a big undertaking considering it isn't natively supported by browsers.

[slevithan]

Unfortunately it is not possible to implement fully accurate backtracking within emulated lookbehind. This will require native lookbehind support.

However, see https://gist.github.com/slevithan/2387872 which shows how to extend XRegExp to add support for infinite-length leading lookbehind.