const EventEmitter = require('events') const self = new EventEmitter() self._nodes = { prevButton: document.querySelectorAll('#week-selector button')[0], nextButton: document.querySelectorAll('#week-selector button')[1], currentWeekText: document.querySelector('#week-selector .current') } self._weekOffset = 0 // copied from http://www.meetingpointmco.nl/Roosters-AL/doc/dagroosters/untisscripts.js, // were using the same code as they do to be sure that we always get the same // week number. self.getCurrentWeek = function (target) { const dayNr = (target.getDay() + 6) % 7 target.setDate(target.getDate() - dayNr + 3) const firstThursday = target.valueOf() target.setMonth(0, 1) if (target.getDay() !== 4) { target.setMonth(0, 1 + ((4 - target.getDay()) + 7) % 7) } return 1 + Math.ceil((firstThursday - target) / 604800000) } self.getSelectedWeek = function () { const now = new Date() const targetDate = new Date(now.getTime() + self._weekOffset * 604800 * 1000) return self.getCurrentWeek(targetDate) } self.updateCurrentWeek = function () { const selectedWeekNumber = self.getSelectedWeek() if (self.getCurrentWeek(new Date()) !== selectedWeekNumber) { self._nodes.currentWeekText.classList.add('changed') } else { self._nodes.currentWeekText.classList.remove('changed') } self.updateDom() self.emit('weekChanged', selectedWeekNumber) } self.updateDom = function () { const selectedWeekNumber = self.getSelectedWeek() let humanReadableWeek = null switch (self._weekOffset) { case 0: humanReadableWeek = 'Huidige week' break case 1: humanReadableWeek = 'Volgende week' break case -1: humanReadableWeek = 'Vorige week' break } if (humanReadableWeek != null) { self._nodes.currentWeekText.textContent = `${humanReadableWeek} • ${selectedWeekNumber}` } else { self._nodes.currentWeekText.textContent = `Week ${selectedWeekNumber}` } } self._handlePrevButtonClick = function () { self._weekOffset -= 1 self.updateCurrentWeek() } self._handleNextButtonClick = function () { self._weekOffset += 1 self.updateCurrentWeek() } self._nodes.prevButton.addEventListener('click', self._handlePrevButtonClick) self._nodes.nextButton.addEventListener('click', self._handleNextButtonClick) module.exports = self