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'.
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.
$ yarn add rrule
Alternatively, download manually:
<script src="rrule/dist/es5/rrule.min.js"></script>
$ yarn add rrule
import { RRule, RRuleSet, rrulestr } from 'rrule'
RRule:
// Create a rule:
const 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:
const 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.
RRule Constructornew 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:
|
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 an array 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 an array of integers, meaning the months to apply the recurrence to. |
bymonthday | If given, it must be either an integer, or an array of integers, meaning the month days to apply the recurrence to. |
byyearday | If given, it must be either an integer, or an array of integers, meaning the year days to apply the recurrence to. |
byweekno | If given, it must be either an integer, or an array 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), an
array of integers, one of the weekday constants
(RRule.MO,
RRule.TU, etc), or an array 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 an array of integers, meaning the hours to apply the recurrence to. |
byminute | If given, it must be either an integer, or an array of integers, meaning the minutes to apply the recurrence to. |
bysecond | If given, it must be either an integer, or an array 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.
rule.optionswkstart). Currently,
rule.options.byweekday isn't equal
to rule.origOptions.byweekday (which is an inconsistency).
rule.origOptionsoptions argument passed to
the constructor.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.
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)
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.
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 Constructornew 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 Functionrrulestr(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.
Timezones: RRule does not implement the TZID keyword in the RFC. It
only correctly supports "floating" times or UTC timezones. While it will work
the same regardless of the host system's timezone, for best results, only pass
in JS Date objects that are represented in UTC to avoid unexpected timezone
offsets being applied.
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)
byweekno is only valid on yearly frequencies, for example).rrule.js is implemented in Typescript. It uses JavaScript Standard Style coding style.
To run the code, checkout this repository and run:
$ yarn
To run the tests, run:
$ yarn test
To build files for distribution, run:
$ yarn build
Python dateutil is written by Gustavo
Niemeyer.
See LICENCE for more details.
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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