rrule

What is rrule?

The 'rrule' npm package is a powerful library for working with recurrence rules as defined in the iCalendar RFC. It allows you to generate and manipulate recurring dates with a high degree of flexibility and precision.

What are rrule's main functionalities?

Generating Recurrence Rules

This feature allows you to generate a set of recurring dates based on a specified rule. In this example, the rule generates dates that occur weekly on Mondays and Fridays, starting from January 1, 2023, and ending on June 1, 2023.

const { RRule } = require('rrule');

const rule = new RRule({
  freq: RRule.WEEKLY,
  interval: 1,
  byweekday: [RRule.MO, RRule.FR],
  dtstart: new Date(Date.UTC(2023, 0, 1, 10, 30)),
  until: new Date(Date.UTC(2023, 5, 1))
});

console.log(rule.all());

Parsing Recurrence Rules

This feature allows you to parse a recurrence rule from a string in the iCalendar format. The example demonstrates how to parse a rule string and generate the corresponding dates.

const { RRule } = require('rrule');

const ruleString = 'FREQ=WEEKLY;INTERVAL=1;BYDAY=MO,FR;DTSTART=20230101T103000Z;UNTIL=20230601T000000Z';
const rule = RRule.fromString(ruleString);

console.log(rule.all());

Converting Recurrence Rules to String

This feature allows you to convert a recurrence rule to its string representation in the iCalendar format. The example shows how to create a rule and then convert it to a string.

const { RRule } = require('rrule');

const rule = new RRule({
  freq: RRule.WEEKLY,
  interval: 1,
  byweekday: [RRule.MO, RRule.FR],
  dtstart: new Date(Date.UTC(2023, 0, 1, 10, 30)),
  until: new Date(Date.UTC(2023, 5, 1))
});

console.log(rule.toString());

Handling Timezones

This feature allows you to handle timezones when working with recurrence rules. The example demonstrates how to create a rule and add it to a rule set, which can then be used to generate dates considering timezones.

const { RRule, RRuleSet, rrulestr } = require('rrule');

const rule = new RRule({
  freq: RRule.WEEKLY,
  interval: 1,
  byweekday: [RRule.MO, RRule.FR],
  dtstart: new Date(Date.UTC(2023, 0, 1, 10, 30)),
  until: new Date(Date.UTC(2023, 5, 1))
});

const ruleSet = new RRuleSet();
ruleSet.rrule(rule);

console.log(ruleSet.all());

Other packages similar to rrule

moment-recur

The 'moment-recur' package extends the Moment.js library to support recurring dates. It is less feature-rich compared to 'rrule' but integrates well with Moment.js for simpler use cases.

later

The 'later' package is a flexible library for defining recurring schedules and executing functions at specified times. It offers more complex scheduling options but is less focused on iCalendar standards compared to 'rrule'.

date-fns

The 'date-fns' package provides a wide range of date utility functions, including some support for recurring dates. It is more general-purpose and less specialized in recurrence rules compared to 'rrule'.

README

rrule.js

Library for working with recurrence rules for calendar dates.

rrule.js supports recurrence rules as defined in the iCalendar RFC, with a few important differences. 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.

---

Quick Start

• Demo app

Client Side

$ bower install rrule

Alternatively, download rrule.js manually. If you intend to use RRule.prototype.toText() or RRule.fromText(), you'll also need nlp.js.

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

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

Server Side

$ npm install rrule

var RRule = require('rrule').RRule
var RRuleSet = require('rrule').RRuleSet
var rrulestr = require('rrule').rrulestr

Usage

RRule:

// Create a rule:
var rule = new RRule({
  freq: 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;DTSTART=20120201T093000Z;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR"

// 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"

RRuleSet:

var rruleSet = new RRuleSet()

// Add a rrule to rruleSet
rruleSet.rrule(new RRule({
  freq: RRule.MONTHLY,
  count: 5,
  dtstart: new Date(2012, 1, 1, 10, 30)
}))

// Add a date to rruleSet
rruleSet.rdate(new Date(2012, 6, 1, 10, 30))

// Add another date to rruleSet
rruleSet.rdate(new Date(2012, 6, 2, 10, 30))

// Add a exclusion rrule to rruleSet
rruleSet.exrule(new r.RRule({
  freq: RRule.MONTHLY,
  count: 2,
  dtstart: new Date(2012, 2, 1, 10, 30)
}))

// Add a exclusion date to rruleSet
rruleSet.exdate(new Date(2012, 5, 1, 10, 30))

// Get all occurrence dates (Date instances):
rruleSet.all()
['Wed Feb 01 2012 10:30:00 GMT+0800 (CST)',
 'Tue May 01 2012 10:30:00 GMT+0800 (CST)',
 'Sun Jul 01 2012 10:30:00 GMT+0800 (CST)',
 'Mon Jul 02 2012 10:30:00 GMT+0800 (CST)']

// Get a slice:
rruleSet.between(new Date(2012, 2, 1), new Date(2012, 6, 2))
['Tue May 01 2012 10:30:00 GMT+0800 (CST)',
 'Sun Jul 01 2012 10:30:00 GMT+0800 (CST)']

 // To string
rruleSet.valueOf()
['RRULE:FREQ=MONTHLY;COUNT=5;DTSTART=20120201T023000Z',
 'RDATE:20120701T023000Z,20120702T023000Z',
 'EXRULE:FREQ=MONTHLY;COUNT=2;DTSTART=20120301T023000Z',
 'EXDATE:20120601T023000Z']

// To string
rruleSet.toString()
'["RRULE:FREQ=MONTHLY;COUNT=5;DTSTART=20120201T023000Z","RDATE:20120701T023000Z,20120702T023000Z","EXRULE:FREQ=MONTHLY;COUNT=2;DTSTART=20120301T023000Z","EXDATE:20120601T023000Z"]'

rrulestr:

// Parse a RRule string, return a RRule object
rrulestr('RRULE:FREQ=MONTHLY;COUNT=5;DTSTART=20120201T023000Z')

// Parse a RRule string, return a RRuleSet object
rrulestr('RRULE:FREQ=MONTHLY;COUNT=5;DTSTART=20120201T023000Z', {forceset: true})

// Parse a RRuleSet string, return a RRuleSet object
rrulestr('RRULE:FREQ=MONTHLY;COUNT=5;DTSTART=20120201T023000Z\nRDATE:20120701T023000Z,20120702T023000Z\nEXRULE:FREQ=MONTHLY;COUNT=2;DTSTART=20120301T023000Z\nEXDATE:20120601T023000Z')

For more examples see python-dateutil documentation.

API

RRule Constructor

new RRule(options[, noCache=false])

The options argument mostly corresponds to the properties defined for RRULE in the iCalendar RFC. Only freq is required.

Option	Description
freq	(required) One of the following constants: RRule.YEARLY RRule.MONTHLY RRule.WEEKLY RRule.DAILY RRule.HOURLY RRule.MINUTELY RRule.SECONDLY
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, RRule.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.nth(+1) or RRule.FR.nth(-1) in byweekday will specify the first or last 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.

noCache: Set to true to disable caching of results. If you will use the same rrule instance multiple times, enabling caching will improve the performance considerably. Enabled by default.

See also python-dateutil documentation.

---

Instance properties

rule.options

Processed options applied to the rule. Includes default options (such us wkstart). Currently, rule.options.byweekday isn't equal to rule.origOptions.byweekday (which is an inconsistency).

<dt><code>rule.origOptions</code></dt>
<dd>The original <code>options</code> argument passed to
the constructor.</dd>

---

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). Dates are being added to the result as long as the iterator returns true. If a false-y value is returned, date isn't added to the result and the iteration is interrupted (possibly prematurely).

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)',
 /* … */]

rule.all(function (date, i){return i < 2})
['Fri Feb 03 2012 10:30:00 GMT+0100 (CET)',
 'Mon Mar 05 2012 10:30:00 GMT+0100 (CET)',]

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().

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)']

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

Returns the first 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. Only properties explicitly specified in options are included:

rule.toString()
"FREQ=WEEKLY;DTSTART=20120201T093000Z;INTERVAL=5;UNTIL=20130130T230000Z;BYDAY=MO,FR"

rule.toString() == RRule.optionsToString(rule.origOptions)
true

RRule.optionsToString(options)

Converts options to iCalendar RFC RRULE string:

// Get full a string representation of all options,
// including the default and inferred ones.
RRule.optionsToString(rule.options)
"FREQ=WEEKLY;DTSTART=20120201T093000Z;INTERVAL=5;WKST=0;UNTIL=20130130T230000Z;BYDAY=MO,FR;BYHOUR=10;BYMINUTE=30;BYSECOND=0"

// Cherry-pick only some options from an rrule:
RRule.optionsToString({
  freq: rule.options.freq,
  dtstart: rule.options.dtstart
})
"FREQ=WEEKLY;DTSTART=20120201T093000Z"

RRule.fromString(rfcString)

Constructs an RRule instance from a complete rfcString:

var rule = RRule.fromString("FREQ=WEEKLY;DTSTART=20120201T093000Z")

// This is equivalent
var rule = new RRule(RRule.parseString("FREQ=WEEKLY;DTSTART=20120201T093000Z"))

RRule.parseString(rfcString)

Only parse RFC string and return options.

var options = RRule.parseString('FREQ=DAILY;INTERVAL=6')
options.dtstart = new Date(2000, 1, 1)
var rule = new RRule(options)

---

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([gettext, [language]])

Returns a textual representation of rule. 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).

var rule = new RRule({
  freq: RRule.WEEKLY,
  count: 23
})
rule.toText()
"every week for 23 times"

RRule.prototype.isFullyConvertibleToText()

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

RRule.fromText(text[, language])

Constructs an RRule instance from text.

rule = RRule.fromText('every day for 3 times')

RRule.parseText(text[, language])

Parse text into options:

options = RRule.parseText('every day for 3 times')
// {freq: 3, count: "3"}
options.dtstart = new Date(2000, 1, 1)
var rule = new RRule(options)

---

RRuleSet Constructor

new RRuleSet([noCache=false])

The RRuleSet instance allows more complex recurrence setups, mixing multiple rules, dates, exclusion rules, and exclusion dates.

Default noCache argument is false, caching of results will be enabled, improving performance of multiple queries considerably.

RRuleSet.prototype.rrule(rrule)

Include the given rrule instance in the recurrence set generation.

RRuleSet.prototype.rdate(dt)

Include the given datetime instance in the recurrence set generation.

RRuleSet.prototype.exrule(rrule)

Include the given rrule instance in the recurrence set exclusion list. Dates which are part of the given recurrence rules will not be generated, even if some inclusive rrule or rdate matches them.

RRuleSet.prototype.exdate(dt)

Include the given datetime instance in the recurrence set exclusion list. Dates included that way will not be generated, even if some inclusive rrule or rdate matches them.

RRuleSet.prototype.all([iterator])

Same as RRule.prototype.all.

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

Same as RRule.prototype.between.

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

Same as RRule.prototype.before.

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

Same as RRule.prototype.after.

---

rrulestr Function

rrulestr(rruleStr[, options])

The rrulestr function is a parser for RFC-like syntaxes. The string passed as parameter may be a multiple line string, a single line string, or just the RRULE property value.

Additionally, it accepts the following keyword arguments:

cache If True, the rruleset or rrule created instance will cache its results. Default is not to cache.

dtstart If given, it must be a datetime instance that will be used when no DTSTART property is found in the parsed string. If it is not given, and the property is not found, datetime.now() will be used instead.

unfold If set to True, lines will be unfolded following the RFC specification. It defaults to False, meaning that spaces before every line will be stripped.

forceset If set to True a rruleset instance will be returned, even if only a single rule is found. The default is to return an rrule if possible, and an rruleset if necessary.

compatible If set to True, the parser will operate in RFC-compatible mode. Right now it means that unfold will be turned on, and if a DTSTART is found, it will be considered the first recurrence instance, as documented in the RFC.

ignoretz If set to True, the date parser will ignore timezone information available in the DTSTART property, or the UNTIL attribute.

tzinfos If set, it will be passed to the datetime string parser to resolve unknown timezone settings. For more information about what could be used here, check the parser documentation.

---

Differences From iCalendar RFC

• RRule has no byday keyword. The equivalent keyword has been replaced by the byweekday keyword, to remove the ambiguity present in the original keyword.
• Unlike documented in the RFC, the starting datetime, dtstart, is not the first recurrence instance, unless it does fit in the specified rules. This is in part due to this project being a port of python-dateutil, which has the same non-compliant functionality. Note that you can get the original behavior by using a RRuleSet and adding the dtstart as an rdate.

var rruleSet = new RRuleSet()
var start = new Date(2012, 1, 1, 10, 30)

// Add a rrule to rruleSet
rruleSet.rrule(new RRule({
  freq: RRule.MONTHLY,
  count: 5,
  dtstart: start
}))

// Add a date to rruleSet
rruleSet.rdate(start)

• Unlike documented in the RFC, every keyword is valid on every frequency (the RFC documents that byweekno is only valid on yearly frequencies, for example).

Development

rrule.js use JavaScript Standard Style coding style.

Changelog

• 2.2.0 (2017-03-11)
  • Added support RRuleSet, which allows more complex recurrence setups, mixing multiple rules, dates, exclusion rules, and exclusion dates.
  • Added Millisecond precision
    • Millisecond offset extracted from dtstart (dtstart.getTime() % 1000)
    • Each recurrence is returned with the same offset
  • Added some NLP support for hourly and byhour.
  • Fixed export in nlp.js.
• 2.1.0
  • Removed dependency on Underscore.js (thanks, @gsf).
  • Various small bugfixes and improvements.
• 2.0.1
  • Added bower.json.
• 2.0.0 (2013-07-16)
  • Fixed a February 28-related issue.
  • More flexible, backwards-incompatible API:
    • freq is now options.freq.
    • options.cache is now noCache.
    • iterator has to return true
    • dtstart and options arguments removed from RRule.fromString (use RRule.parseString and modify options manually instead).
    • today argument removed from Rule.prototype.toText (never actually used).
    • rule.toString() now includes DTSTART (if explicitly specified in options).
    • Day constants .clone is now .nth, eg. RRule.FR.nth(-1) (last Friday).
  • Added RRule.parseString
  • Added RRule.parseText
  • Added RRule.optionsToString
• 1.1.0 (2013-05-21)
  • Added a demo app.
  • Handle dates in UNTIL in RRule.fromString.
  • Added support for RequireJS.
  • Added options argument to RRule.fromString.
• 1.0.1 (2013-02-26)
  • Fixed leap years (thanks @jessevogt)
• 1.0.0 (2013-01-24)
  • Fixed timezone offset issues related to DST (thanks @evro).
• 1.0.0-beta (2012-08-15)
  • Initial public release.

Authors

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

Python dateutil is written by Gustavo Niemeyer.

See LICENCE for more details.