Very cool, but the most useful thing to me about Rubular (which this is inspired by) was the quick reference. Considering the results you get for a google search on "JavaScript Regex", a nice simple table with the basic syntax (and methods) would be very valuable. After that, the fact I can test expressions on the page is just gravy. I can test expressions on any page in the world with Dev Tools.

I had built one that allows to write counter examples also, here an example http://bit.ly/dV4nRg

Bug: line 125 of application.js should read

if (index !== -1) value = value.slice(index + length);

That's cool - a reference would be good as well. I've always used RegExr[1] which combines such documentation really neatly.

1. http://gskinner.com/RegExr/

Cool, although i don't think this will replace http://regexpal.com/ as my favourite regex tester.

Just added Quick Reference, thanks for the feedback!