posixtz

This package contains functions for working with POSIX time zones.

Install

posixtz depends on moment and moment-timezone as peer dependencies. You must install them yourself:

npm install posixtz moment moment-timezone

API

posixtz exports these functions:

• formatPosixTZ
• parsePosixTZ
• getOffsetForLocalDateWithPosixTZ
• formatLocalDateWithOffset

Import them like this:

const {
  formatPosixTZ,
  parsePosixTZ,
  getOffsetForLocalDateWithPosixTZ,
  formatLocalDateWithOffset
} = require('posixtz');

Or like this:

import {
  formatPosixTZ,
  parsePosixTZ,
  getOffsetForLocalDateWithPosixTZ,
  formatLocalDateWithOffset
} from 'posixtz';

formatPosixTZ

formatPosixTZ accepts an IANA time zone string and an optional year (defaults to current year) and returns a POSIX time zone string for that year.

> formatPosixTZ('America/Los_Angeles', 2018)
'PST8PDT,M3.2.0,M11.1.0'

parsePosixTZ

parsePosixTZ accepts a POSIX time zone string and returns an object like this:

> parsePosixTZ('PST8PDT,M3.2.0,M11.1.0')
{ stdAbbr: 'PST',
  stdOffset: 480,
  dst: true,
  dstAbbr: 'PDT',
  dstOffset: 420,
  dstStart: { month: 3, week: 2, day: 0, hour: 2, minute: 0, second: 0 },
  dstEnd: { month: 11, week: 1, day: 0, hour: 2, minute: 0, second: 0 } }

getOffsetForLocalDateWithPosixTZ

getOffsetForLocalDateWithPosixTZ accepts a date/time string and a POSIX time zone string and returns a the offset from UTC (in minutes) on that date and at that time based on whether daylight savings time was in effect or not.

> getOffsetForLocalDateWithPosixTZ('2018-03-11T02:00:00', 'PST8PDT,M3.2.0,M11.1.0')
-420

formatLocalDateWithOffset

formatLocalDateWithOffset accepts a date/time string and a POSIX time zone string and formats it as ISO 8601 plus the offset computed from the POSIX time zone string.

> formatLocalDateWithOffset('2018-03-11T02:00:00', 'PST8PDT,M3.2.0,M11.1.0')
'2018-03-11T02:00:00-07:00'

Dependencies

moment and moment-timezone are currently required, but I would like it to use luxon or Intl, if possible.

Acknowledgements

The code for the format function originally came from this Moment.js GitHub issue:

• https://github.com/moment/moment-timezone/issues/314

Resources

More information on POSIX time zones here:

• https://www.ibm.com/developerworks/aix/library/au-aix-posix/index.html
• http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html