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rrecur

v2.0.0

Published

Convert between RFC2445 RRULE and its JSON equivalent. Useful with rrule.js.

Downloads

326

Readme

rrecur

Convert between RFC2445 RRULE and its JSON equivalent AND see the future (and past). Useful with rrule.js.

If you want UIs like these:

Google Calendar: http://imgur.com/a/gT7Af

Thunderbird Calendar: http://imgur.com/a/LhnWU

Kendo Calendar: http://imgur.com/a/zVLyg

You need a schedule-logic library like this to actually interpret RRULEs and schedule the events.

Usage

parse & stringify

This snippet will work both in the Browser and with Node.js (hence the scary bit at the bottom).

From JSON to RRULE

(function (exports) {
  'use strict';

  var Rrecur = exports.Rrecur || require('rrecur').Rrecur
    , rfcString
    ;

  // every other month on the first and last sunday
  rfcString = Rrecur.stringify({
    "freq": "monthly"
  , "interval": "2"
  , "count": "10"
  , "byday": ["1su","-1su"]
  });

}('undefined' !== typeof exports && exports || new Function('return this')()));

From RRULE to JSON

(function (exports) {
  'use strict';

  var Rrecur = exports.Rrecur || require('rrecur').Rrecur
    , rfcString
    , rruleObject
    ;

  rfcString = "RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU";
  rruleObject = Rrecur.parse(rfcString);

  // Also supports sans-RRULE prefix plus DTSTART for the sake of `rrule.js` compatability
  rfcString = "DTSTART=20140616T103000Z;FREQ=DAILY;BYHOUR=10;BYMINUTE=30;BYSECOND=0;UNTIL=20150616T153000Z";
  rruleObject = Rrecur.parse(rfcString);

}('undefined' !== typeof exports && exports || new Function('return this')()));

next occurrence of an event

Scenario: I want an alarm to go off every day at 10:30am, given my location.

Since we can't specify timezones with a JavaScript date object, we pretend internally that local time is zoneless time. UTC is handled exactly as UTC.

So let's say it's 8:00am on our server in Utah on the first day of summer and we want to set an alarm for 10:30am in New York (30 minutes from now) every mon, wed, fri:

var rrecur
  ;

rrecur = Rrecur.create({
  dtstart: {
    zoneless: Rrecur.toLocaleISOString(new Date(2014,06,21, 10,30,0), "GMT-0400 (EDT)")
    // OR utc: new Date(2014,06,21, 10,30,0).toISOString()
  , locale: "GMT-0400 (EDT)"
  }
, rrule: {
    freq: 'daily'
  , until: Rrecur.toAdjustedISOString(new Date(2014,06,22, 10,30,0), "GMT-0400 (EDT)")
  , count: 1
  , byhour: [10]
  , byminute: [30]
  , byday: ['mo','we','fr'] // Or [Rrecur.weekdays[1], Rrecur.weekdays[3], Rrecur.weekdays[5]]
  // `bysecond` will default to 00, since that's what's specified in `dtstart`
  }
}, new Date());

rrecur.next(); // 2014-05-21T10:30:00.000-0400

If you didn't specify locale then you would get back a time in UTC or in GMT-0600 (MDT) that you would need to manually adjust.

Whether you specify zoneless or utc, you must still specify locale.

one-time events

var rrecur
  ;

rrecur = Rrecur.create({
  dtstart: {
    locale: new Date(2014,06,21, 10,30,0).toString()
  }
, rrule: null
}, new Date());

// Assuming you specified the Date on a machine running on MDT
rrecur.next(); // 2014-07-21T16:30:00.000-0000

For one-time events you may simply use a locale string, which will be converted into to both zoneless and utc for internal purposes.

Also, rrule will be automatically populated to match the zoneless dtstart.

Installation

browser

NOTE: you only need rrecur.js for the basic JSON <-> RRULE conversion. If you want to actually find the occurances you'll need underscore.js, rrule.js, and moment.js, and rrecur-iterator.js. However, in some future version I may be able to eliminate underscore.js and rrule.js.

via bower

bower install rrecur

via download

wget https://raw2.github.com/coolaj86/rrecurjs/master/rrecur.js
wget https://raw2.github.com/coolaj86/rrecurjs/master/rrecur-iterator.js

and insert the script tag, of course

<script src="underscore.js"></script>
<script src="rrule.js"></script>
<script src="moment.js"></script>
<script src="rrecur.js"></script>
<script src="rrecur-iterator.js"></script>
script(src="underscore.js")
script(src="rrule.js")
script(src="moment.js")
script(src="rrecur.js")
script(src="rrecur-iterator.js")

I know, it's a lot of dependencies... but that's just how it is. In a future version it may be reasonable to drop underscore and rrule (or at least substitute lodash for underscore), but moment is a must. JavaScript's Date object is just too messed up.

node.js

npm install rrecur

API

Convert between RFC2445 RRULE and its JSON equivalent.

  • Rrecur.parse(rruleStr) - parses a string rrule (allows non-standard dtstart in string)
  • Rrecur.stringify(rruleObj) - stringifies an rrule object (allows non-standard dtstart)

Find the next (or previous) occurence of an event in an rrule chain.

  • Rrecur.create(rrule, localeDateString) - creates a wrapped instance from rrule.js from an rrule object or string
    • localeDateString - a string such as Wed Jul 16 2014 10:30:00 GMT-0400 (EDT)
    • Rrecur#previous() - cycles backwards through time to find a previous instance up to dtstart
    • Rrecur#next() - cycles forwards through time to find the next instance up to until or count

Utility functions

  • Rrecur.toLocaleISOString(date, [locale]) - ouput an ISO string with timezone information
    • 2014-06-21T10:00:00.000-0600 instead of Sat Jun 21 2014 10:15:08 GMT-0600 (MDT) or 2014-06-21T16:00:00.000Z
    • If locale is specified in a format such as -04:00 or GMT-0400 (EDT), the local (not UTC) time is still used, but the offset is replaced with the supplied locale.
  • Rrecur.toAdjustedISOString(date, locale)
    • date - A local date object (with the wrong timezone)
    • locale A JavaScript Locale string (or Date string) with the desired timezone
    • returns a UTC string adjusted to accurately represent the desired timezone

RRULEs

You put in an object like this:

{ "freq": "weekly"
, "until": "2015-01-01T10:30:00.000Z"
, "byday": ["tu", "th"]
, "byhour": [4]
, "byminute": [30]
}
  • freq - yearly|monthly|weekly|daily|hourly|minutely|secondly
  • interval - bi-weekly, tri-weekly, etc
  • bymonth
  • byweekno
  • byyearday
  • bymonthday
  • byday - 0-7, su,mo,tu,we,th,fr,sa,su
  • byhour
  • byminute
  • bysecond
  • until - seems that this must be given in UTC as per spec, which is weird
  • count - how many occurrences
  • wkst - which day the week starts on 0-7, sa,su,mo
  • bysetpos - not sure how this works - http://www.kanzaki.com/docs/ical/recur.html
  • dtstart - specifies the first event (or a date close to it), non-standard as part of rrule, but is part of ical
    • If you don't specify dtstart, the current time will be used.
    • You cannot get previous() before dtstart
  • locale - specifies the locale in the format GMT-0500 (EST) - non-standard, in general
  • tzid - specifies the locale, non-standard as part of rrule, but is part of ical

See https://github.com/jkbr/rrule#api for implementation details.

Examples

JSON version of iCal RRULE

{ "freq": "daily"
, "until": "2015-01-01T10:30:00.000Z"
, "byday": ["tu", "th"]
, "byhour": [4]
, "byminute": [30]
}

Non-standard iCal directive

(once TZID is implemented, this will be standard)

DTSTART;LOCALE=GMT-0500 (EST):20140616T103000
RRULE:FREQ=DAILY;BYHOUR=10;BYMINUTE=30;BYSECOND=0;UNTIL=20150616T153000Z

Non-standard iCal directive (rrule.js-flavored)

DTSTART=20140616T103000Z;FREQ=DAILY;BYHOUR=10;BYMINUTE=30;BYSECOND=0;UNTIL=20150616T153000Z

Appendix

Because I needed a place to rant.

Timezones

Timezones are a PAIN! Right!?

We take care of the hard brainwork for you, but just so you know:

Here are the problems:

  • JavaScript's native Date object has only two options - Locale and UTC
  • The server may have a different locale than the client
  • rrule.js only operates on Locale - the local time of the server
  • RRULEs are zoneless - 10:30am is meant to be in the user's time
  • DTSTART;TZID=America/New_York isn't yet supported by rrule.js

Here are solutions:

  • DTSTART you can include LOCALE (recommended) or use UTC (confusing)
  • UNTIL you must use UTC (confusing, but that's the way it is)
    • Try Rrecur.toAdjustedISOString(new Date(2014,06,16,10,30,00), 'GMT-0600 (MDT)')
  • RRULEs are zoneless, but we do our best to put them in the right zone.
  • Everything is calculated in local time under the hood.

Remember:

  • Always specify RRULEs in local time (except DTSTART and UNTIL in UTC).
    • An RRULE for Monday at 10am will fire well after the sun is risen whether in California or China
    • An RRULE for Monday at 10am will have a different UTC conversion in California than in China
    • dtstart should always be in UTC or in local time with a locale
    • until must be specified in UTC
    • all calculations will be done in the local time of the server