rruleByPattern.js

Build recurrence rules by patterns / templates like '111100' (i.e. 4 on, 2 off)

It is a rrule.js extension that gives more flexibility in creation of recurring events. The pattern / template can be absolutely custom and as long as you need. This extension is well suited for shift plan (rota, roster) set ups.

Quick Start

• Demo app

Install

$ yarn add rrule-by-pattern
# or
$ npm install rrule-by-pattern

Alternatively, download manually:

• rruleByPattern.min.js (bundled without rrule.js, minified)
• rruleByPattern.js (bundled without rrule.js, not minified)

As rrule.js is not bundled with rruleByPattern.js, it's needed to install or download it as well.

<script src="./rrule-by-pattern/dist/es5/rruleByPattern.min.js"></script>

Then you will be able to use global variable rruleByPattern (e.g. new rruleByPattern.ShortRRuleSetBuilder()).

Usage

There are 2 builders. One builds readable rrule sets, another - short.

Both builders need 3 arguments: rruleSet, pattern, count.

The rruleSet is a rrule.js RRuleSet obviously and it should be built and then passed to the builder. The builder will build a new RRuleSet based on the passed one.

The pattern is just an array of 0 and 1:

• 0 exclude date (e.g. shift off);
• 1 include date (e.g. shift on).

The count is a number of dates you want to have in a built RRuleSet. For sets that have 'until' or 'count', it can be just rruleSet.count(). For unlimited sets you should pick a count by yourself.

ReadableRRuleSetBuilder:

import { RRule, RRuleSet } from 'rrule'
import { ReadableRRuleSetBuilder } from 'rrule-by-pattern'

const rruleSet = new RRuleSet()

rruleSet.rrule(new RRule({
    freq: RRule.HOURLY,
    dtstart: new Date(Date.UTC(2025, 11, 25, 6)),
    until: new Date(Date.UTC(2025, 11, 30, 18)),
    interval: 12
}))

rruleSet.rrule(new RRule({
    freq: RRule.DAILY,
    dtstart: new Date(Date.UTC(2026, 0, 1, 6)),
    until: new Date(Date.UTC(2026, 0, 30, 6)),
}))

// Original RRuleSet string
rruleSet.toString()
DTSTART:20251225T060000Z
RRULE:FREQ=HOURLY;UNTIL=20251230T180000Z;INTERVAL=12
DTSTART:20260101T060000Z
RRULE:FREQ=DAILY;UNTIL=20260130T060000Z

const pattern: Array<0|1> = [1,1,1,1,0,0]

const builder = new ReadableRRuleSetBuilder(
    rruleSet,
    pattern,
    rruleSet.count()
)

const newRRuleSet = builder.build()

// Built RRuleSet string
newRRuleSet.toString()
DTSTART:20251225T060000Z
RRULE:FREQ=HOURLY;UNTIL=20251230T180000Z;INTERVAL=12
DTSTART:20260101T060000Z
RRULE:FREQ=DAILY;UNTIL=20260130T060000Z
EXDATE:20251227T060000Z,20251227T180000Z,20251230T060000Z,20251230T180000Z,20260105T060000Z,20260106T060000Z,20260111T060000Z,20260112T060000Z,20260117T060000Z,20260118T060000Z,20260123T060000Z,20260124T060000Z,20260129T060000Z,20260130T060000Z

ShortRRuleSetBuilder:

import { RRule, RRuleSet } from 'rrule'
import { ShortRRuleSetBuilder } from 'rrule-by-pattern'

const rruleSet = new RRuleSet()

rruleSet.rrule(new RRule({
    freq: RRule.HOURLY,
    dtstart: new Date(Date.UTC(2025, 11, 25, 6)),
    until: new Date(Date.UTC(2025, 11, 30, 18)),
    interval: 12
}))

rruleSet.rrule(new RRule({
    freq: RRule.DAILY,
    dtstart: new Date(Date.UTC(2026, 0, 1, 6)),
    until: new Date(Date.UTC(2026, 0, 30, 6)),
}))

// Original RRuleSet string
rruleSet.toString()
DTSTART:20251225T060000Z
RRULE:FREQ=HOURLY;UNTIL=20251230T180000Z;INTERVAL=12
DTSTART:20260101T060000Z
RRULE:FREQ=DAILY;UNTIL=20260130T060000Z

const pattern: Array<0|1> = [1,1,1,1,0,0]

const builder = new ShortRRuleSetBuilder(
    rruleSet,
    pattern,
    rruleSet.count()
)

const newRRuleSet = builder.build()

// Built RRuleSet string
newRRuleSet.toString()
DTSTART:20250101T060000Z
RRULE:FREQ=YEARLY;UNTIL=20251231T235959Z;BYDAY=MO,TU,WE,TH,FR,SA,SU;BYSETPOS=359,360,362,363
DTSTART:20250101T180000Z
RRULE:FREQ=YEARLY;UNTIL=20251231T235959Z;BYDAY=MO,TU,WE,TH,FR,SA,SU;BYSETPOS=359,360,362,363
DTSTART:20260101T060000Z
RRULE:FREQ=YEARLY;UNTIL=20261231T235959Z;BYDAY=MO,TU,WE,TH,FR,SA,SU;BYSETPOS=1,2,3,4,7,8,9,10,13,14,15,16,19,20,21,22,25,26,27,28

Development

rruleByPattern.js is implemented in TypeScript.

To run the code, checkout this repository and run:

$ yarn

To run the tests, run:

$ yarn test

To build the test coverage, run:

$ yarn coverage

To build files for distribution, run:

$ yarn build