Add 'GCal' link to all the dates in the the programme on the de Oosterpoort website.

deoosterpoort-to-gcal.user.js

// ==UserScript==
// @name          GCal links for De Oosterpoort
// @namespace     http://ikhoefgeen.nl/userscripts
// @description	  Create Google Calendar events directly from De Oosterpoort website
// @include       http://www.de-oosterpoort.nl/programma/*
// ==/UserScript==

var DeOosterpoort = {}

DeOosterpoort.findData = function(root)
{
	var header = root.querySelector('#main h1'),
		specs = root.querySelectorAll("#main .detail-info table tr"),
		event = new iCal.Event;

	if (!header || specs.length == 0)
		return null;

	event.name = getText(header);

	for (var i = 0; i < specs.length; ++i)
	{
		// If it doesn't have at least two table data fields, skip it.
		if (!specs[i].querySelector('td + td'))
			continue;

		var label = specs[i].querySelector('td').textContent.trim(),
			value = (specs[i].querySelector('td + td > span')
				? specs[i].querySelector('td + td > span')
				: specs[i].querySelector('td + td')).textContent.trim();

		switch (label)
		{
			case 'Datum':
				DeOosterpoort.parseDatum(value, event);
				break;

			case 'Tijdstip':
				DeOosterpoort.parseTijdstip(value, event);
				break;

			case 'Locatie':
				event.location = value;
				break;
		}
	}

	console.log(event);

	return event;
};

DeOosterpoort.parseDatum = function(datum, event)
{
	var parts = datum.match(/^\w+\ (\d+) (\w+) (\d+)$/);

	if (!parts)
		throw "Could not parse string '" + datum + "' as a date.";

	var month = [
		'januari', 'februari', 'maart',
		'april', 'mei', 'juni',
		'juli', 'augustus', 'september',
		'oktober', 'november', 'december'
	].indexOf(parts[2]);

	['from', 'till'].forEach(function(range) {
		event[range].setYear(parts[3]);
		event[range].setMonth(month);
		event[range].setDate(parts[1]);
	});

	return true;
};

DeOosterpoort.parseTijdstip = function(tijdstip, event)
{
	var parts = tijdstip.match(/^(\d{1,2}):(\d\d)(?:\s+tot (\d{1,2}):(\d\d))?$/);
	
	if (!parts)
		throw "Could not parse '" + tijdstip + "' as a time.";
	
	event.from.setHours(parts[1]);
	event.from.setMinutes(parts[2]);

	if (typeof parts[3] !== 'undefined' && typeof parts[4] !== 'undefined')
	{
		event.till.setHours(parts[3]);
		event.till.setMinutes(parts[4]);
	}
	else
	{
		event.till.setHours(parseInt(parts[1]) + 1);
		event.till.setMinutes(parts[2]);
	}

	return true;
}

function align(length, filler, value)
{
	value = "" + value; // now it is a string for sure! :P
	return repeat(filler, length - value.length) + value;
}

function repeat(character, times)
{
	var output = '';

	while (times-- > 0)
		output += character;
	
	return output;
}

function getText(node)
{
	return node.textContent.replace(/\s+/gm, ' ').trim();
}

var iCal = {};

iCal.Event = function() {
	this.from = new Date;
	this.till = new Date;
	this.name = '[name]';
	this.location = '[location]';
	this.link = document.location.href;
}

iCal.Event.prototype.toGoogleCalendarLink = function()
{
	var ical_format = 'Ymd\THis\Z';

	return [
		'http://www.google.com/calendar/event?action=TEMPLATE',
		'text=' + encodeURIComponent(this.name),
		'dates=' + iCal.formatDate(ical_format, this.from) + '/' + iCal.formatDate(ical_format, this.till),
		'location=' + encodeURIComponent(this.location),
		'details=' + encodeURIComponent(this.link),
		'trp=true',
		'sprop=De+Oosterpoort',
		'sprop=name:' + encodeURIComponent(this.link)
	].join("&");
}

iCal.formatDate = function(format, date)
{
	var output = '';

	for (var i = 0; i < format.length; ++i)
	{
		switch (format[i])
		{
			case '\\':
				output += format[++i];
				break;
			
			case 'Y':
				output += date.getUTCFullYear();
				break;
			
			case 'm':
				output += align(2, '0', date.getUTCMonth() + 1);
				break;
			
			case 'd':
				output += align(2, '0', date.getUTCDate());
				break;
			
			case 'H':
				output += align(2, '0', date.getUTCHours());
				break;
			
			case 'i':
				output += align(2, '0', date.getUTCMinutes());
				break;
			
			case 's':
				output += align(2, '0', date.getUTCSeconds());
				break;
			
			default:
				output += format[i];
				break;
		}
	}

	return output;
}

function main()
{
	var event = DeOosterpoort.findData(document);

	if (!event)
		return;
	
	var lookup_link = document.createElement('a');
	lookup_link.style.fontSize = '0.8em';
	lookup_link.style.marginLeft = '1ch';
	lookup_link.href = 'https://www.google.com/calendar/render?tab=mc&date=' + iCal.formatDate('Ymd', event.from);
	lookup_link.target = '_blank';
	lookup_link.appendChild(document.createTextNode('show in GCal'));

	document.querySelector('#main .detail-info td+td').appendChild(lookup_link);
	
	var link = document.createElement('a');
	link.style.float = 'right';
	link.style.fontSize = '0.8em';
	link.href = event.toGoogleCalendarLink();
	link.target = '_blank';
	link.appendChild(document.createTextNode('Add to GCal'));

	document.querySelector('#main .detail-info td+td').appendChild(link);
}

main();