frequency

Temporal frequency library

Installation

npm install --save date-frequency

Usage

createFrequency()
  .on('hour', 10)
  .on('minute', 30)
  .next(); // next occurence of 10:30

// or, with a ISO-inspired string format
createFrequency('FT10M30')
  .next(); // next occurence of 10:30

createFrequency()
  .on('day', 2, 'week')
  .next(); // next Tuesday

// all occurences of 10:00:00 in the next 5 days
const d = new Date();
createFrequency()
  .on('hour', 10)
  .on('m', 0)
  .on('s', 0)
  .between(d, (new Date(+d)).setDate(d.getDate() + 5));

Methods

createFrequency()

Constructor takes a string notation or rules object.

createFrequency('F3D/WT10H30M0S'); // every Wednesday at 10:30:00

// equals to:
createFrequency({D: {W: 3}, h: {D: 10}, m: {h: 30}, s: {m: 0}});

.on(unit, value[, scope])

Add frequency rules by specifying a unit, a value to fix it to and, optionally, a scope.

frequency.on('hour', 10).on('minute', 0).on('second', 0);
// each day at 10:00:00

frequency.on('day', 6).on('m', 30);
// each 30 minutes after the hour of the 6th day of each month

frequency.on('d', 7, 'week');
// Sundays at midnight

The value argument can also be a string which matches the name of a predefined function available in the fn property of the constructor.

createFrequency.fn.even = require('number-kind').even;
createFrequency()
	.on('week', 'even', 'epoch')
	.on('h', 0)
	.on('m', 0)
	.on('s', 0);
// days of even weeks at midnight

.next([date])

Returns the next occurence of the frequency after or on the specified date. Please note that you are responsible for incrementing the date if you want to call .next() multiple times to get consecutive occurences. If no date is specified, new Date() is used.

.between(start, end)

Returns all occurences of the frequency between (and including) the specified start and end date.

.toString()

Returns a string notation of the frequency.

Development

• Clone repo & npm install.
• Lint: npm run lint.
• Test: npm test.