crossbrowser regex danger (and the danger of chrome as your only test browser)

Today we found out the hard way that
return string.replace(/(?<!')'{2,2}(?!')/g,
(meant to replace double apostrophes with single, but leave 3 or more alone) will work on chrome but not Safari or Firefox.

Similarly, Firefox doesn't seem to support the //s operator for multiline matches.

So be careful. And don't just test in chrome!