Mathias Bynens Reporter
	Description • 10 years ago

The behavior for `Date.UTC()` is undefined even in the ES6 draft spec. But it would be good to align with other implementations.

Results for:

    [ Date.UTC(), Date.UTC(1) ]

Safari/JavaScriptCore: [ NaN, NaN ]
Chrome/Opera/V8: [ NaN, NaN ]
Safari/JavaScriptCore: [ NaN, NaN ]
Old Opera/Carakan: [ NaN, NaN ]

Only Firefox and IE11 return a non-`NaN` value: [ -2208988800000, -2177452800000 ]

Consider returning `NaN` in such cases to match the majority of other engines.

	Boris Zbarsky [:bzbarsky]
	Comment 1 • 10 years ago

This is why a spec is needed.

Date.UTC(0) returns the same thing as Date.UTC(undefined) and Date.UTC() in at least Firefox and Chrome.  So this is not just about missing arguments; it's about different behavior after you coerce the argument to a number.

So what is the actual behavior you're asking us to implement?

	Boris Zbarsky [:bzbarsky]
	Comment 2 • 10 years ago

Oh, I see, fewer than two arguments, ok.

	Mathias Bynens Reporter
	Comment 3 • 10 years ago

(In reply to Boris from comment #1)
> So what is the actual behavior you're asking us to implement?

(In reply to Boris from comment #2)
> Oh, I see, fewer than two arguments, ok.

I don’t actually have a preference – I’d just like all implementations to align. The simplest way to make that happen is to convince Firefox/SpiderMonkey and IE/Chakra to return `NaN` for `Date.UTC` calls with fewer than two arguments, but if everyone else is willing to change, that’s fine too.

The spec bug is here, in case you have a strong opinion: https://bugs.ecmascript.org/show_bug.cgi?id=3112

	Shu-yu Guo [:shu]
	Comment 4 • 7 years ago

This is now specced, and we should update our implementation: https://tc39.github.io/ecma262/#sec-date.utc

	André Bargull [:anba] Assignee
	Comment 5 • 7 years ago

This is covered by test262, so I didn't need to write new tests. \o/

I'll update the patch to use the correct git hash as soon as https://github.com/tc39/ecma262/pull/642 is merged.

	Shu-yu Guo [:shu]
	Comment 6 • 7 years ago

Comment on attachment 8837575 [details] [diff] [review]
bug1050755.patch

Review of attachment 8837575 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks for the patch.

	Tom S [:evilpie]
	Comment 7 • 7 years ago

The pull request has been merged.

	André Bargull [:anba] Assignee
	Comment 8 • 7 years ago

Updated patch to apply cleanly on inbound, no functional changes. Carrying r+ from shu.

	André Bargull [:anba] Assignee
	Comment 9 • 7 years ago

(In reply to Tom Schuster [:evilpie] from comment #7)
> The pull request has been merged.

Thanks for pinging bterlson to merge the PR!

	André Bargull [:anba] Assignee
	Comment 10 • 7 years ago

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=98e20233106bdb669ea02ca4cf6745faa48c6e94

	Pulsebot
	Comment 11 • 7 years ago

Pushed by cbook@mozilla.com:
https://hg.mozilla.org/integration/mozilla-inbound/rev/4db4dc2a4620
Allow to call Date.UTC with fewer than two arguments per ES2017. r=shu

	Carsten Book [:Tomcat]
	Comment 12 • 7 years ago
bugherder

https://hg.mozilla.org/mozilla-central/rev/4db4dc2a4620

	Florian Scholz (Open Web Docs)
	Comment 13 • 7 years ago

https://developer.mozilla.org/en-US/Firefox/Releases/54#JavaScript
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/UTC#Compatibility_notes