shift-timezone-offset

Converts timezoned dates to local time or any other timezone.

Sometimes it's easier to work in local time, because all JavaScript Date objects are given in local time:

``js
new Date('2017-01-01T00:00:00Z').getHours()

// => 11
`

It's because my timezone is +11:00, fine, but I would like a 0!

This library will shift a date to match time in the local timezone, or the one you need, as if the timezone information is ignored.

example

Working in local time:

`js
// process.env.TZ = 'Pacific/Noumea' // local timezone

var timezoneShift = require('../')
var dateInfo = '2017-01-01T00:00:00+03:00'
var initialDate = new Date(dateInfo)

console.log(initialDate.getHours())
// => 8

console.log(initialDate.getTime() / 1000)
// => 1483218000

var converter = timezoneShift('+03:00') // timezoneShift(dateInfo) works as well
var localDate = converter.toLocal(initialDate)

console.log(localDate.getHours())
// => 0

console.log(localDate.getTime() / 1000)
// => 1483189200

var backToInitialDate = converter.fromLocal(localDate)

console.log(backToInitialDate.getHours())
// => 8

console.log(backToInitialDate.getTime() / 1000)
// => 1483218000
`

When only one operation is needed, there is a shortcut notation:

`js
var timezoneShift = require('../')
var dateInfo = '2017-01-01T12:00:00+03:00'

console.log(new Date(dateInfo))
// => 2017-01-01T09:00:00.000Z

// 5 hours timezone shift
console.log(timezoneShift.convert(dateInfo, { from: '+03:00', to: '+08:00' }))
// => 2017-01-01T04:00:00.000Z

// to local (all 3 are similar)
// "to" defaults to local timezone:
console.log(timezoneShift.convert(dateInfo, { from: '+03:00' }))
// => 2017-01-01T01:00:00.000Z

// to be sure:
console.log(timezoneShift.convert(dateInfo, { from: '+03:00', to: '+11:00' }))
// => 2017-01-01T01:00:00.000Z

// even simpler ("from" timezone is infered from date string):
console.log(timezoneShift.convert(dateInfo))
// => 2017-01-01T01:00:00.000Z
`

api

`js
var timezoneShift = require('timezone-offset')
`

var converter = timezoneShift(validTimezone)

* validTimezone - valid ISO 8601 date string or timezone string: '+05:00', '-1100' or '2017-01-01T12:00:00+05:00'. An offset is valid as well: -240 in place of '+04:00.

$3

Shift a date considered in the converter timezone to the local timezone. It means the absolute UTC value is affected.
Returns a new Date object.

* date - any valid value for the Date constructor.

$3

Shift a local date to the timezone. It means the UTC value is affected.
Returns a new Date object.

* date - any valid value for the Date constructor.

$3

Shift a local date to converter timezone.
Returns a new Date object.

* date - any valid value for the Date constructor.
* zone - valid ISO 8601 date string or timezone string.

$3

Timezone offset from UTC in minutes (similar to Date.prototype.getTimezoneOffset).

$3

The full shift in minutes required to convert the dates to the local timezone.

timezoneShift.convert(date, zones)

* date - any valid value for the Date object constructor.
* zone - object containing initial and final timezones:
* zones.from - valid timezone info. Could be infered if date is an ISO date string.
* zones.to - default: local timezone. Valid timezone info.

license

MIT

install

`
npm install shift-timezone-offset
``