rrule.js: Library for working with recurrence rules for calendar dates.

rrule.js supports recurrence rules as defined in the iCalendar RFC. It is a partial port of the rrule module from the excellent python-dateutil library. On top of that, it supports parsing and serialization of recurrence rules from and to natural language.

The only dependency is Underscore.js.

• Quick Start
  • Client Side
  • Server Side
  • Usage
• API
  • RRule Constructor
  • Occurrence Retrieval Methods
  • iCalendar RFC String Methods
  • Natural Language Text Methods
• Authors

Quick Start

Client Side

Download rrule.js. If you want to use RRule.prototype.toText() or RRule.fromText(), you'll also need nlp.js.

<script src="underscore.js"></script>
<script src="rrule/rrule.js"></script>

<!-- Optional -->
<script src="rrule/nlp.js"></script>

Server Side

npm -g install rrule

var RRule = require('rrule').RRule;

Usage

// Create a rule:
var rule = new RRule(RRule.WEEKLY, {
    interval: 5,
    byweekday: [RRule.MO, RRule.FR],
    dtstart: new Date(2012, 1, 1, 10, 30),
    until: new Date(2012, 12, 31)
});

// Get all occurrence dates (Date instances):
rule.all();
['Fri Feb 03 2012 10:30:00 GMT+0100 (CET)',
 'Mon Mar 05 2012 10:30:00 GMT+0100 (CET)',
 'Fri Mar 09 2012 10:30:00 GMT+0100 (CET)',
 'Mon Apr 09 2012 10:30:00 GMT+0200 (CEST)',
 /* … */]

// Get a slice:
rule.between(new Date(2012, 7, 1), new Date(2012, 8, 1))
['Mon Aug 27 2012 10:30:00 GMT+0200 (CEST)',
 'Fri Aug 31 2012 10:30:00 GMT+0200 (CEST)']

// Get an iCalendar RRULE string representation:
// The output can be used with RRule.fromString().
rule.toString();
"FREQ=WEEKLY;BYDAY=MO,FR;INTERVAL=5;UNTIL=20130130T230000Z"

// Get a human-friendly text representation:
// The output can be used with RRule.fromText().
rule.toText()
"every 5 weeks on Monday, Friday until January 31, 2013"

For more examples see test/tests.js and python-dateutil documentation.

API

RRule Constructor

rule = new RRule(freq, options)

The freq is one of the following constants:

• RRule.YEARLY
• RRule.MONTHLY
• RRule.WEEKLY
• RRule.DAILY
• RRule.HOURLY
• RRule.MINUTELY
• RRule.SECONDLY

The optional options argument is an object that can specify one or more of the following options:

Option	Description
cache	If given, it must be a boolean value specifying to enable or disable caching of results. If you will use the same rrule instance multiple times, enabling caching will improve the performance considerably.
dtstart	The recurrence start. Besides being the base for the recurrence, missing parameters in the final recurrence instances will also be extracted from this date. If not given, new Date will be used instead.
interval	The interval between each freq iteration. For example, when using RRule.YEARLY, an interval of 2 means once every two years, but with RRule.HOURLY, it means once every two hours. The default interval is 1.
wkst	The week start day. Must be one of the RRule.MO, RRule.TU, RRule.WE constants, or an integer, specifying the first day of the week. This will affect recurrences based on weekly periods. The default week start is RRule.MO.
count	How many occurrences will be generated.
until	If given, this must be a Date instance, that will specify the limit of the recurrence. If a recurrence instance happens to be the same as the Date instance given in the until argument, this will be the last occurrence.
bysetpos	If given, it must be either an integer, or a sequence of integers, positive or negative. Each given integer will specify an occurrence number, corresponding to the nth occurrence of the rule inside the frequency period. For example, a bysetpos of -1 if combined with a RRule.MONTHLY frequency, and a byweekday of (RRule.MO, RRule.TU, RRule.WE, RRule.TH, FR), will result in the last work day of every month.
bymonth	If given, it must be either an integer, or a sequence of integers, meaning the months to apply the recurrence to.
bymonthday	If given, it must be either an integer, or a sequence of integers, meaning the month days to apply the recurrence to.
byyearday	If given, it must be either an integer, or a sequence of integers, meaning the year days to apply the recurrence to.
byweekno	If given, it must be either an integer, or a sequence of integers, meaning the week numbers to apply the recurrence to. Week numbers have the meaning described in ISO8601, that is, the first week of the year is that containing at least four days of the new year.
byweekday	If given, it must be either an integer (0 == RRule.MO), a sequence of integers, one of the weekday constants (RRule.MO, RRule.TU, etc), or a sequence of these constants. When given, these variables will define the weekdays where the recurrence will be applied. It's also possible to use an argument n for the weekday instances, which will mean the nth occurrence of this weekday in the period. For example, with RRule.MONTHLY, or with RRule.YEARLY and BYMONTH, using RRule.FR.clone(+1) in byweekday will specify the first friday of the month where the recurrence happens. Notice that the RFC documentation, this is specified as BYDAY, but was renamed to avoid the ambiguity of that argument.
byhour	If given, it must be either an integer, or a sequence of integers, meaning the hours to apply the recurrence to.
byminute	If given, it must be either an integer, or a sequence of integers, meaning the minutes to apply the recurrence to.
bysecond	If given, it must be either an integer, or a sequence of integers, meaning the seconds to apply the recurrence to.
byeaster	This is an extension to the RFC specification which the Python implementation provides. Not implemented in the JavaScript version.

See also python-dateutil documentation.

Occurrence Retrieval Methods

RRule.prototype.all([iterator])

Returns all dates matching the rule. It is a replacement for the iterator protocol this class implements in the Python version.

As rules without until or count represent infinite date series, you can optionally pass iterator, which is a function that is called for each date matched by the rule. It gets two parameters date (the Date instance being added), and i (zero-indexed position of date in the result). If the function returns false, the iteration is interrupted (possibly prematurely).

RRule.prototype.between(after, before, inc=false [, iterator])

Returns all the occurrences of the rrule between after and before. The inc keyword defines what happens if after and/or before are themselves occurrences. With inc == true, they will be included in the list, if they are found in the recurrence set.

Optional iterator has the same function as it has with RRule.prototype.all().

RRule.prototype.after(dt, inc=false)

Returns the last recurrence before the given Date instance. The inc argument defines what happens if dt is an occurrence. With inc == true, if dt itself is an occurrence, it will be returned.

RRule.prototype.before(dt, inc=false)

Returns the last recurrence after the given Date instance. The inc argument defines what happens if dt is an occurrence. With inc == true, if dt itself is an occurrence, it will be returned.

See also python-dateutil documentation.

iCalendar RFC String Methods

RRule.prototype.toString()

Returns a string representation of the rule as per the iCalendar RFC.

RRule.fromString(rfcString)

Constructs an RRule instance from rfcString.

Natural Language Text Methods

These methods provide an incomplete support for text–RRule and RRule–text conversion. You should test them with your input to see whether the result is acceptable.

To use these methods in the browser, you need to include the rrule/nlp.js file as well.

RRule.prototype.toText(rrule, [today, [gettext, [language]]])

Returns a textual representation of rule. You need to pass today only when the rule has the until option. The gettext callback, if provided, will be called for each text token and its return value used instead. The optional language argument is a language definition to be used (defaults to rrule/nlp.js:ENGLISH).

RRule.prototype.isFullyConvertibleToText()

Provides a hint on whether all the options the rule has are convertible to text.

RRule.fromText(text[, dtstart[, language]])

Constructs an RRule instance from text.

Authors

• Jakub Roztocil (@jakubroztocil)
• Lars Schöning (@lyschoening)

Python dateutil is written by Gustavo Niemeyer.

See LICENCE for more details.