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.
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());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.
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'.
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'.
####################################################################### 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_.
.. contents:: :local: :backlinks: none
Download rrule.js. If you want to use RRule.prototype.toText()
or RRule.fromText(), you'll also need nlp.js.
.. code-block:: html
<script src="underscore.js"></script>
<script src="rrule/rrule.js"></script>
<!-- Optional -->
<script src="rrule/nlp.js"></script>
.. code-block:: bash
npm -g install rrule
.. code-block:: javascript
var RRule = require('rrule').RRule;
.. code-block:: javascript
// 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.
RRule Constructor.. code-block:: javascript
rule = new RRule(freq, options)
The freq is one of the following constants:
RRule.YEARLYRRule.MONTHLYRRule.WEEKLYRRule.DAILYRRule.HOURLYRRule.MINUTELYRRule.SECONDLYThe 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.
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.
RRule.prototype.toString()
Returns a string representation of the rule as per the iCalendar RFC.
RRule.fromString(rfcString)
Constructs an RRule instance from rfcString.
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.
Jakub Roztocil_ (@jakubroztocil_)@lyschoening_)Python dateutil is written by Gustavo Niemeyer_.
See LICENCE_ for more details.
.. _rrule.js: https://raw.github.com/jkbr/rrule/master/rrule.js .. _nlp.js: https://raw.github.com/jkbr/rrule/master/nlp.js .. _iCalendar RFC: http://www.ietf.org/rfc/rfc2445.txt .. _python-dateutil: http://labix.org/python-dateutil/ .. _Underscore.js: http://underscorejs.org/ .. _Jakub Roztocil: http://roztocil.name/ .. _@jakubroztocil: http://twitter.com/jakubroztocil .. _@lyschoening: http://twitter.com/lyschoening .. _Gustavo Niemeyer: http://niemeyer.net/ .. _LICENCE: https://github.com/jkbr/rrule/blob/master/LICENCE .. _test/tests.js: https://github.com/jkbr/rrule/blob/master/test/tests.js
FAQs
JavaScript library for working with recurrence rules for calendar dates.
The npm package rrule receives a total of 384,167 weekly downloads. As such, rrule popularity was classified as popular.
We found that rrule demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 2 open source maintainers collaborating on the project.
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