Bug 283825 – non standard new Date('2024-12-3') yields to Invalid Date

• Status: NEW
• Component: JavaScriptCore

[Sebastian Schlatow]

new Date('2024-12-3') yields to: Invalid Date

Date.parse('2024-12-3') yields to: NaN

Firefox:

new Date('2024-12-3') yields to: Date Tue Dec 03 2024 00:00:00 GMT+0100 (Central European Standard Time)

Date.parse('2024-12-3') yields to: 1733180400000

Chromium:

new Date('2024-12-3') yields to: Tue Dec 03 2024 00:00:00 GMT+0100 (Central European Standard Time)

Date.parse('2024-12-3') yields to: 1733180400000

[Karl Dubost]

> the value produced by this function is implementation-defined when given any String value that does not conform to the Date Time String Format (21.4.1.32) and that could not be produced in that implementation by the toString or toUTCString method.

While this leads to an identical result in Firefox and Chrome. 
Per sec this is an implementation defined format. 

https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-date-time-string-format

@Sebastian,

did you notice a website breaking because of this?

[Karl Dubost]

The valid format per spec is `YYYY-MM-DDTHH:mm:ss.sssZ` or a truncation of it.

[Sebastian Schlatow]

> did you notice a website breaking because of this?

@Karl yes, our inhouse webapp, but we found a work around ;)

But nonetheless it would be great if it were more robust.

[Radar WebKit Bug Importer]

<rdar://problem/141044926>

[Karl Dubost]

Bug 223166 is the bug for the implementation of Temporal.
It doesn't fix this specific issue, but it helps figure out the priorities. 
It would be interesting to dig if there have been more compat issues reported because of this.

[Karl Dubost]

The code might be here. 
https://searchfox.org/wubkat/rev/52d16c972a163b36fe64a99efb66af93c6e2f2b2/Source/WTF/wtf/DateMath.cpp#728-762

[Karl Dubost]

ha no, this was for "2024/12/03".
The standard parsing with dashese is at 
https://searchfox.org/wubkat/rev/52d16c972a163b36fe64a99efb66af93c6e2f2b2/Source/WTF/wtf/DateMath.cpp#616-673

[Karl Dubost]

which calls parseES5DatePortion(std::span<const LChar>& currentPosition, int& year, long& month, long& day)
https://searchfox.org/wubkat/rev/52d16c972a163b36fe64a99efb66af93c6e2f2b2/Source/WTF/wtf/DateMath.cpp#448-490