When building a UTC date with Moment.js, zone() setter does nothing (2.8.3)

[ghost]

I get the exact same moment object after running zone(-1) as I do when I don't run it. Example:

console.log( moment().utc().toDate() );
console.log( moment().utc().zone(-1).toDate() );

I would expect this to adjust the Date object according to the timezone offset, but it does... well, nothing.

[icambron]

Moment keeps track of instances in time (i.e. milliseconds since 1970 UTC). What you're doing when you say utc() or zone(), you're changing how that time is expressed (i.e. we say "9:00" in EST but "6:00" in PST, but it's the same time). So converting it back in to a date drops the "you should print dates differently" metadata. It's still the same time.

It sounds like you want to modify the actual time? We don't have a "mutate the time so that it will be displayed the same way in this other zone" feature, though, we've discussed it (or do we, @ichernev?)

[ghost]

Yes, I want to modify the actual time. This is pretty limiting and I will likely have to stop using this library because of this limitation.

[icambron]

@rquinlivan I dug a little deeper. You can pass a second argument to zone() to make it keep the wall-clock time the same:

> moment().format()
'2014-09-15T16:59:30-04:00'
> moment().zone(-1).format()
'2014-09-15T21:59:35+01:00'
> moment().zone(-1, true).format()
'2014-09-15T16:59:38+01:00'

So you'll end up with:

> moment().toDate()
Mon Sep 15 2014 17:00:16 GMT-0400 (EDT)
> moment().zone(-1, true).toDate()
Mon Sep 15 2014 12:00:19 GMT-0400 (EDT)

Which I believe is what you want.

FWIW, everyone will be quicker to help you with open source if you approach a functionality gap with "hey, I need this feature, how can I help?" rather than as you did.