rrule.js
========

Library for working with recurrence rules for calendar dates.

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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.

*

$3

- Demo app

#### Client Side

``bash
$ yarn add rrule
`

Alternatively, download manually:

* rrule.min.js (bundled, minified)
* rrule.js (bundled, not minified)
* rrule-tz.min.js (with timezone support, bundled, minified)
* rrule-tz.js (with timezone support, bundled, not minified)

`html

`

#### Server Side

Includes optional TypeScript types

`bash
$ yarn add rrule


or


$ npm install rrule
`

#### Usage

RRule:
`es6
import { RRule, RRuleSet, rrulestr } from 'rrule'

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

// Get all occurrence dates (Date instances):
rule.all()
[ '2012-02-03T10:30:00.000Z',
'2012-03-05T10:30:00.000Z',
'2012-03-09T10:30:00.000Z',
'2012-04-09T10:30:00.000Z',
'2012-04-13T10:30:00.000Z',
'2012-05-14T10:30:00.000Z',
'2012-05-18T10:30:00.000Z',

/ … /]

// Get a slice:
rule.between(new Date(Date.UTC(2012, 7, 1)), new Date(Date.UTC(2012, 8, 1)))
['2012-08-27T10:30:00.000Z',
'2012-08-31T10:30:00.000Z']

// Get an iCalendar RRULE string representation:
// The output can be used with RRule.fromString().
rule.toString()
"DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;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:
`js
const rruleSet = new RRuleSet()

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

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

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

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

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

// Get all occurrence dates (Date instances):
rruleSet.all()
[ '2012-02-01T10:30:00.000Z',
'2012-05-01T10:30:00.000Z',
'2012-07-01T10:30:00.000Z',
'2012-07-02T10:30:00.000Z' ]

// Get a slice:
rruleSet.between(new Date(Date.UTC(2012, 2, 1)), new Date(Date.UTC(2012, 6, 2)))
[ '2012-05-01T10:30:00.000Z', '2012-07-01T10:30:00.000Z' ]


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

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

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

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

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

`

$3

Dates in JavaScript are tricky. RRule tries to support as much flexibility as possible without adding any large required 3rd party dependencies, but that means we also have some special rules.

By default, RRule deals in "floating" times or UTC timezones. If you want results in a specific timezone, RRule also provides timezone support. Either way, JavaScript's built-in "timezone" offset tends to just get in the way, so this library simply doesn't use it at all. All times are returned with zero offset, as though it didn't exist in JavaScript.

The bottom line is the returned "UTC" dates are always meant to be interpreted as dates in your local timezone. This may mean you have to do additional conversion to get the "correct" local time with offset applied.

For this reason, it is highly recommended to use timestamps in UTC eg. new Date(Date.UTC(...)). Returned dates will likewise be in UTC (except on Chrome, which always returns dates with a timezone offset).

For example:

`ts
// local machine zone is America/Los_Angeles
const rule = RRule.fromString(
"DTSTART;TZID=America/Denver:20181101T190000;\n"
+ "RRULE:FREQ=WEEKLY;BYDAY=MO,WE,TH;INTERVAL=1;COUNT=3"
)
rule.all()

[ 2018-11-01T18:00:00.000Z,
2018-11-05T18:00:00.000Z,
2018-11-07T18:00:00.000Z ]
// Even though the given offset is Z (UTC), these are local times, not UTC times.
// Each of these this is the correct local Pacific time of each recurrence in
// America/Los_Angeles when it is 19:00 in America/Denver, including the DST shift.

// You can get the local components by using the getUTC* methods eg:
date.getUTCDate() // --> 1
date.getUTCHours() // --> 18
`

If you want to get the same times in true UTC, you may do so eg. using Luxon:

`ts
rule.all().map(date =>
DateTime.fromJSDate(date)
.toUTC()
.setZone('local', { keepLocalTime: true })
.toJSDate()
)

[ 2018-11-02T01:00:00.000Z,
2018-11-06T02:00:00.000Z,
2018-11-08T02:00:00.000Z ]
// These times are in true UTC; you can see the hours shift
`

For more examples see
python-dateutil documentation.

*

$3

Optionally, it also supports use of the TZID parameter in the
RFC
when the Luxon library is provided. The
specification
and support matrix for Luxon apply.

Example with TZID:

`js
new RRule({
dtstart: new Date(Date.UTC(2018, 1, 1, 10, 30)),
count: 1,
tzid: 'Asia/Tokyo'
}).all()

// assuming the system timezone is set to America/Los_Angeles, you get:
[ '2018-01-31T17:30:00.000Z' ]
// which is the time in Los Angeles when it's 2018-02-01T10:30:00 in Tokyo.
`

Whether or not you use the TZID param, make sure to only use JS Date objects that are
represented in UTC to avoid unexpected timezone offsets being applied, for example:

`js
// WRONG: Will produce dates with TZ offsets added
new RRule({
freq: RRule.MONTHLY,
dtstart: new Date(2018, 1, 1, 10, 30),
until: new Date(2018, 2, 31)
}).all()

[ '2018-02-01T18:30:00.000Z', '2018-03-01T18:30:00.000Z' ]

// RIGHT: Will produce dates with recurrences at the correct time
new RRule({
freq: RRule.MONTHLY,
dtstart: new Date(Date.UTC(2018, 1, 1, 10, 30)),
until: new Date(Date.UTC(2018, 2, 31))
}).all()

[ '2018-02-01T10:30:00.000Z', '2018-03-01T10:30:00.000Z' ]
`

$3

#### RRule Constructor

`javascript
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. IMPORTANT: See the discussion under timezone support
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.
tzid	If given, this must be a string supported by Luxon, and the Luxon library must be provided. See discussion under Timezone support.
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.


*


#### 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).

rule.origOptions

The original options argument passed to
the constructor.


*


#### 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).

`javascript
rule.all()
[ '2012-02-01T10:30:00.000Z',
'2012-05-01T10:30:00.000Z',
'2012-07-01T10:30:00.000Z',
'2012-07-02T10:30:00.000Z' ]

rule.all(function (date, i){return i < 2})
[ '2012-02-01T10:30:00.000Z',
'2012-05-01T10:30:00.000Z' ]
`

##### 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().

`javascript
rule.between(new Date(Date.UTC(2012, 7, 1)), new Date(Date.UTC(2012, 8, 1)))
['2012-08-27T10:30:00.000Z',
'2012-08-31T10:30:00.000Z']
`

##### 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:

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

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

##### RRule.optionsToString(options)

Converts options to iCalendar RFC RRULE string:

`javascript
// Get full a string representation of all options,
// including the default and inferred ones.
RRule.optionsToString(rule.options)
"DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;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
})
"DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;"
`

##### RRule.fromString(rfcString)

Constructs an RRule instance from a complete rfcString:

`javascript
var rule = RRule.fromString("DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY;")

// This is equivalent
var rule = new RRule(RRule.parseString("DTSTART:20120201T093000Z\nRRULE:FREQ=WEEKLY"))
`

##### RRule.parseString(rfcString)

Only parse RFC string and return options.

`javascript
var options = RRule.parseString('FREQ=DAILY;INTERVAL=6')
options.dtstart = new Date(Date.UTC(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.

##### 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).

`javascript
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.

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

##### RRule.parseText(text[, language])

Parse text into options:

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


*

#### RRuleSet Constructor

`javascript
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. NOTE: EXRULE has been (deprecated
in RFC 5545)[https://icalendar.org/iCalendar-RFC-5545/a-3-deprecated-features.html]
and does not support a DTSTART property.

##### 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.tzid(tz?)
Sets or overrides the timezone identifier. Useful if there are no rrules in this
RRuleSet and thus no DTSTART.

##### 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.

##### RRuleSet.prototype.rrules()

Get list of included rrules in this recurrence set.

##### RRuleSet.prototype.exrules()

Get list of excluded rrules in this recurrence set.

##### RRuleSet.prototype.rdates()

Get list of included datetimes in this recurrence set.

##### RRuleSet.prototype.exdates()

Get list of excluded datetimes in this recurrence set.

*

#### rrulestr Function

`js
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.

tzid
If given, it must be a string that will be used when no TZID property is found
in the parsed string. If it is not given, and the property is not found, 'UTC'
will be used by default.


*

$3

* 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.

`javascript
var rruleSet = new RRuleSet()
var start = new Date(Date.UTC(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).

$3

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
`

#### Authors

* Jakub Roztocil
(@jakubroztocil)
* Lars Schöning (@lyschoening)
* David Golightly (@davigoli)

Python dateutil` is written by Gustavo
Niemeyer.

See LICENCE for
more details.

[npm-url]: https://npmjs.org/package/rrule
[npm-image]: http://img.shields.io/npm/v/rrule.svg

[ci-url]: https://github.com/jakubroztocil/rrule/actions
[ci-image]: https://github.com/jakubroztocil/rrule/workflows/Node%20CI/badge.svg

[downloads-url]: https://npmjs.org/package/rrule
[downloads-image]: http://img.shields.io/npm/dm/rrule.svg?style=flat-square

[js-standard-url]: https://github.com/feross/standard
[js-standard-image]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat

[gitter-url]: https://gitter.im/rrule-js/Lobby
[gitter-image]: https://img.shields.io/gitter/room/nwjs/nw.js.svg

#### Related projects

* https://rrules.com/ — RESTful API to get back occurrences of RRULEs that conform to RFC 5545.