/timezone-soft

parse informal timezone names

Primary LanguageJavaScript

parse abbreviated, sloppy, and informal timezone names
npm install timezone-soft
by Spencer Kelly
(formerly called 'spacetime-informal') 

import soft from 'timezone-soft'

// get an IANA tz from user input
let timezones = soft('milwaukee')[0]
/*[{
    iana: 'America/Chicago',
    standard: { name: 'Central Standard Time', abbrev: 'CST' },
    daylight: { name: 'Central Daylight Time', abbrev: 'CDT' }
  }
]*/

IANA timezone codes are the official reference for timezone information, and is what you should use, whenever possible.

Humans though, are goofballs, and use a whole different informal scheme:

  • In (North) America: PST, MST, EST...
  • in Europe (lately): WEST, CEST, EEST...
  • in Africa: EAT, CAT, WAST...
  • in Australia: AWST, AEDT, ACST...

these line-up with the IANA codes sometimes.

...other times they don't.

These names also collide -

'IST' is used to mean:

  • 'Indian Stardard Time'
  • 'Irish Stardard Time'
  • 'Israeli Stardard Time'

These names also produce all-sorts of ambiguities, regarding DST-changes-

Both Winnipeg and Mexico City are CST, but have a much different DST schedule: image

(thanks timeanddate.com!)

-of course, there's a bunch of political/historical/disputed stuff going on, too. Apologies if this library steps into that unknowingly.

...so that's what we're trying to fix - to 'soften' this exchange, between human and IANA timezone nomenclature, using some opinionated-but-common-sense rules and decision-making.

It was originally built for use in the spacetime timezone library.

Usage

const soft = require('timezone-soft')

soft('EST')
// 'America/New_York'

soft('central')
// 'America/Chicago'

soft('venezuela')
// 'America/Caracas'

soft('south east asia')
// 'Asia/Bangkok'

Typescript/Deno/Webpack:

import soft from 'timezone-soft'

it was built to be as forgiving as possible, and return the most common-sense IANA timezone id from user-input.

DST

Often, the proper timezone name will depend on which date you are referencing. You can reckon this pretty-easily with spacetime, like this:

const spacetime = require('spacetime')
const soft = require('timezone-soft')

let display = soft('montreal')[0]
let show = display.standard.abbrev

// are we in standard time, or daylight time?
let s = spacetime.now(display.iana)
if (display.daylight && s.isDST()) {
  show = display.daylight.abbrev
}
console.log(s.time() + ' ' + show)
// '4:20pm EDT'

work-in-progress!

See also

MIT