Only { x | abs(x) < 1 } can have a leading 0 At most 1 leading zero is allowed there MUST be at least one digit after the decimal point ONLY a digit or a minus sign can start a number

I will test perf on this before reviewing.

The JSONParserState additions aren't commented, according with the current entries. That's changing in bug 564621, whose patch is finished but which can't land quite yet for yak-shaving reasons. However, the JSONParserState documentation can be split out of it, so I'm going to do that now so you can make additions here without having them either undocumented or anomalously documented. The rest of those changes should (fingers crossed) have minimal intersection with the patch here.

Pushed those docs changes, so you should be able to update the patch with docs for the JSONParserState changes now: http://hg.mozilla.org/tracemonkey/rev/db4607b00594 You may fire when ready, Gridley.

The parser rewrite fixes this. (And sigh, yet another patch that got left dangling. :-( )

Fixed by the parser rewrite in bug 589664.

For the record, rejecting leading zeroes broke someone's intranet application. Worth knowing, perhaps, although I don't think we should do anything about it (nor should we have done differently at the time if we'd known): http://whereswalden.com/2011/06/06/i-feel-the-need-the-need-for-json-parsing-correctness-and-speed/#comment-153900 They targeted Firefox 3 and 4 only, hence why no other browser complained to make them fix.