Moment-timezone: Wrong timeZone returned from guess() on chrome mobile android

[mieszko4]

Hi,
I am using Samsung Galaxy S5 with newest chrome installed (Version 55.0.2883.91).
I switched to 'Asia/Shanghai' timezone (GMT+0800). This is China Standard Time - CST

However, moment.tz.guess() returns me 'America/Chicago' which is Central Standard Time - CST.
On Linux Mint, Chrome (Version 55.0.2883.87 (64-bit)) timezone is correct.

After digging a bit in the code, I figured out that the problem is that moment first tries to use information about timezone from: Intl.DateTimeFormat().resolvedOptions().timeZone which returns the wrong timezone on mobile. If I comment out detection from Intl guess() returns the right timezone.

From googling around I concluded that Intl stuff is still not too reliable. Could you add a flag for guess() so that it is possible to switch off detection through Intl?

[mieszko4]

My workaround:

import moment from "moment-timezone";

export default function guessTimezone() {
  const supportsIntl = typeof global.Intl !== undefined;
  let oldIntl;
  let timezone;

  // do not use buggy Intl for timezone guess
  // See: https://github.com/moment/moment-timezone/issues/441
  if (supportsIntl) {
    oldIntl = global.Intl;
    global.Intl = undefined;
    timezone = moment.tz.guess();
    global.Intl = oldIntl;
  } else {
    timezone = moment.tz.guess();
  }

  return timezone;
}

[maggiepint]

Sorry for the late reply, but yeah, that's a pretty reasonable enhancement request.

[artemijan]

@maggiepint , I have the same issue on Linux mint 18 & chrome Version 57.0.2987.110 (64-bit).
Any updates?

[chanphillip]

Got the same issue.

[jayvolr]

moment.tz.guess() returns'UTC' for me on Ubuntu 16.04 using Chrome Version 57.0.2987.133 (64-bit).

I expected it to return 'America/New_York'

[bolasblack]

I encountered this issue too, on Chrome 60, 61 for Mac, I found if I switch timezone to another timezone and then switch back, Intl.DateTimeFormat().resolvedOptions().timeZone will return the correct value. But new Date().getTimezoneOffset() will be 0...

[mjrust]

@bolasblack something like RangeError: Expected Area/Location(/Location)* for time zone, got Etc/GMT+7? I expect it to be 'America/Phoenix'. How do I fix?

[mj1856]

Dup #423