Date.parse('1-1-2012') returns NaN in Firefox but 1325404800000 in Chrome, Edge, and IE11

Assigned to



JavaScript: Standard Library
2 years ago
6 months ago


(Reporter: cpeterson, Assigned: tephra)


(Blocks: 1 bug)


Firefox Tracking Flags

(firefox46 affected, firefox47 affected, firefox48 affected, firefox49 affected, firefox-esr38 affected, firefox-esr45 affected)


(Whiteboard: [parity-chrome][parity-edge][parity-ie])



2 years ago reports a number of Date.parse() problems, but the Firefox problems mostly stem from the parsing of dates with dash delimiters:

GOOD: Date.parse('1/1/2012') returns 1325404800000 Chrome, Edge, IE11, Firefox, and Safari.

BAD: Date.parse('1-1-2012') returns 1325404800000 in Chrome, Edge, and IE11 but NaN in Firefox and Safari.
Component: JavaScript Engine → JavaScript: Standard Library
Duplicate of this bug: 1341481

Comment 2

6 months ago
I've been lurking around some of theses Date.parse bugs/feature requests and decided to start working on them.

As far as I can see we previously supported the '1-1-2012' format (there is even commented out code for this) but
seems to have decided to support dates with the format 'Wed Nov 05 21:49:11 GMT-0800 1997', where the tz offset comes
before the year, instead.

A very simple solution is to just remove the out-commented check on line 1020 at the expense of the format where the year comes last. I'm looking into how much work it is to get support for both formats.


6 months ago
Assignee: nobody → eric
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