ical/example_rrule.js

A tolerant, minimal icalendar parser

var ical = require('./node-ical')
var moment = require('moment')

var data = ical.parseFile('./examples/example_rrule.ics');

// Complicated example demonstrating how to handle recurrence rules and exceptions.

for (var k in data) {

	// When dealing with calendar recurrences, you need a range of dates to query against,
	// because otherwise you can get an infinite number of calendar events.
	var rangeStart = moment("2017-01-01");
	var rangeEnd = moment("2017-12-31");


	var event = data[k]
	if (event.type === 'VEVENT') {

		var title = event.summary;
		var startDate = moment(event.start);
		var endDate = moment(event.end);

		// Calculate the duration of the event for use with recurring events.
		var duration = parseInt(endDate.format("x")) - parseInt(startDate.format("x"));

		// Simple case - no recurrences, just print out the calendar event.
		if (typeof event.rrule === 'undefined')
		{
			console.log('title:' + title);
			console.log('startDate:' + startDate.format('MMMM Do YYYY, h:mm:ss a'));
			console.log('endDate:' + endDate.format('MMMM Do YYYY, h:mm:ss a'));
			console.log('duration:' + moment.duration(duration).humanize());
			console.log();
		}

		// Complicated case - if an RRULE exists, handle multiple recurrences of the event.
		else if (typeof event.rrule !== 'undefined')
		{
			// For recurring events, get the set of event start dates that fall within the range
			// of dates we're looking for.
			var dates = event.rrule.between(
			  rangeStart.toDate(),
			  rangeEnd.toDate(),
			  true,
			  function(date, i) {return true;}
			)

			// The "dates" array contains the set of dates within our desired date range range that are valid
			// for the recurrence rule.  *However*, it's possible for us to have a specific recurrence that
			// had its date changed from outside the range to inside the range.  One way to handle this is
			// to add *all* recurrence override entries into the set of dates that we check, and then later
			// filter out any recurrences that don't actually belong within our range.
			if (event.recurrences != undefined)
			{
				for (var r in event.recurrences)
				{
					// Only add dates that weren't already in the range we added from the rrule so that 
					// we don't double-add those events.
					if (moment(new Date(r)).isBetween(rangeStart, rangeEnd) != true)
					{
						dates.push(new Date(r));
					}
				}
			}

			// Loop through the set of date entries to see which recurrences should be printed.
			for(var i in dates) {

				var date = dates[i];
				var curEvent = event;
				var showRecurrence = true;
				var curDuration = duration;

				startDate = moment(date);

				// Use just the date of the recurrence to look up overrides and exceptions (i.e. chop off time information)
				var dateLookupKey = date.toISOString().substring(0, 10);

				// For each date that we're checking, it's possible that there is a recurrence override for that one day.
				if ((curEvent.recurrences != undefined) && (curEvent.recurrences[dateLookupKey] != undefined))
				{
					// We found an override, so for this recurrence, use a potentially different title, start date, and duration.
					curEvent = curEvent.recurrences[dateLookupKey];
					startDate = moment(curEvent.start);
					curDuration = parseInt(moment(curEvent.end).format("x")) - parseInt(startDate.format("x"));
				}
				// If there's no recurrence override, check for an exception date.  Exception dates represent exceptions to the rule.
				else if ((curEvent.exdate != undefined) && (curEvent.exdate[dateLookupKey] != undefined))
				{
					// This date is an exception date, which means we should skip it in the recurrence pattern.
					showRecurrence = false;
				}

				// Set the the title and the end date from either the regular event or the recurrence override.
				var recurrenceTitle = curEvent.summary;
				endDate = moment(parseInt(startDate.format("x")) + curDuration, 'x');

				// If this recurrence ends before the start of the date range, or starts after the end of the date range, 
				// don't process it.
				if (endDate.isBefore(rangeStart) || startDate.isAfter(rangeEnd)) {
					showRecurrence = false;
				}

				if (showRecurrence === true) {

					console.log('title:' + recurrenceTitle);
					console.log('startDate:' + startDate.format('MMMM Do YYYY, h:mm:ss a'));
					console.log('endDate:' + endDate.format('MMMM Do YYYY, h:mm:ss a'));
					console.log('duration:' + moment.duration(curDuration).humanize());
					console.log();
				}

			}
		} 
	}
}