main.js

// Source on github: https://github.com/love2d/love-wiki-version-picker
function versionpicker() {
	var picker = document.createElement('select');

	picker.onchange = function () {
		applyFilter(this.options[this.selectedIndex].value);
	}

	function array (a) {
		return [].slice.apply(a || []);
	}

	// Some helpers for localStorage, basically resort to doing nothing
	// if it isn't available.
	function storeValue(name, value) {
		try {
			localStorage[name] = value;
		}
		catch (e) {
		}
	}

	function retrieveValue(name) {
		try {
			return localStorage[name];
		}
		catch (e) {
			return undefined;
		}
	}

	var pickerVersions = {};

	function injectPickerOption (version, text) {
		if (pickerVersions[version]) {
			return;
		}
		pickerVersions[version] = true;

		var option = document.createElement('option');

		option.value = version;
		option.textContent = text;
		picker.appendChild(option);
	}

	function makeWrapper () {
		var wrapper = document.createElement('div');

		wrapper.setAttribute('data-love-filterable', true);

		return wrapper;
	}

	function wrapSections () {
		var element = document.querySelector('.mw-parser-output > h2');
		var wrapper;

		while (element) {
			var next = element.nextSibling;
			if (element.nodeName == 'H2') {
				wrapper = makeWrapper();
				element.parentNode.insertBefore(wrapper, element);
			}
			wrapper.appendChild(element);
			element = next;
		}
	}

	function updateSectionFromNote (section, note) {
		if (note.getAttribute('data-newin') !== null) {
			var version = note.getAttribute('data-newin');
			if (version.startsWith('[[')) {
				version = version.substring(2, version.length-2);
			}
			section.setAttribute('data-love-version-added', version);
			note.setAttribute('data-love-version-note', true);
		}
		if (note.getAttribute('data-oldin') !== null) {
			var version = note.getAttribute('data-oldin');
			if (version.startsWith('[[')) {
				version = version.substring(2, version.length-2);
			}
			section.setAttribute('data-love-version-removed', version);
			note.setAttribute('data-love-version-note', true);
		}
		if (note.getAttribute('data-deprecatedin') !== null) {
			var version = note.getAttribute('data-deprecatedin');
			if (version.startsWith('[[')) {
				version = version.substring(2, version.length-2);
			}
			section.setAttribute('data-love-version-deprecated', version);
		}
	}

	function QueryIterator (query) {
		return function (callback) {
			return array(document.querySelectorAll(query)).forEach(callback);
		}
	}

	var withSections = QueryIterator('*[data-love-filterable]');
	var withAdded = QueryIterator('*[data-love-version-added]');
	var withRemoved = QueryIterator('*[data-love-version-removed]');
	var withAddedRemoved = QueryIterator('*[data-love-version-added][data-love-version-removed]');
	var withDeprecated = QueryIterator('*[data-love-version-deprecated]');
	var withNotes = QueryIterator('*[data-love-version-note]');

	function hideNotes () {
		withNotes(function (note) { note.style.display = 'none' });
	}

	function showNotes () {
		withNotes(function (note) { note.style.display = null });
	}

	var needsFilter = false;

	function scanSections () {
		withSections(function (section) {
			var note = section.querySelector('table');
			if (!note) {
				return;
			}
			updateSectionFromNote(section, note);
			while (note.nextSibling && note.nextSibling.tagName == 'TABLE') {
				note = note.nextSibling;
				updateSectionFromNote(section, note);
			}
			needsFilter = true;
		});
	}

	function scanTables () {
		var added = document.querySelectorAll('.smwtable *[alt="Added since"] + *');
		var removed = document.querySelectorAll('.smwtable *[alt="Removed in"] + *');
		var deprecated = document.querySelectorAll('.smwtable *[alt="Deprecated in"] + *');

		array(added).forEach(function (a) {
			var e = a.parentNode.parentNode;
			e.setAttribute('data-love-filterable', true);
			e.setAttribute('data-love-version-added', a.title);
			needsFilter = true;
		});
		array(removed).forEach(function (a) {
			var e = a.parentNode.parentNode;
			e.setAttribute('data-love-filterable', true);
			e.setAttribute('data-love-version-removed', a.title);
			needsFilter = true;
		});
		array(deprecated).forEach(function (a) {
			var e = a.parentNode.parentNode;
			e.setAttribute('data-love-filterable', true);
			e.setAttribute('data-love-version-deprecated', a.title);
			needsFilter = true;
		});
	}

	// return true if 'installed' is greater than or equal to 'required'
	// http://stackoverflow.com/a/6832670
	function compareVersions (installed, required) {
		var a = installed.split('.');
		var b = required.split('.');

		for (var i = 0; i < a.length; ++i) {
			a[i] = Number(a[i]);
		}
		for (var i = 0; i < b.length; ++i) {
			b[i] = Number(b[i]);
		}
		if (a.length == 2) {
			a[2] = 0;
		}
		if (b.length == 2) {
			b[2] = 0;
		}

		if (a[0] > b[0]) return true;
		if (a[0] < b[0]) return false;

		if (a[1] > b[1]) return true;
		if (a[1] < b[1]) return false;

		if (a[2] > b[2]) return true;
		if (a[2] < b[2]) return false;

		return true;
	}

	function filterVersion (installed) {
		filterAll(hideNotes);
		withAdded(function (section) {
			var required = section.getAttribute('data-love-version-added');
			if (!compareVersions(installed, required)) {
				section.style.display = 'none';
			}
		});
		withRemoved(function (section) {
			var removed = section.getAttribute('data-love-version-removed');
			if (compareVersions (installed, removed)) {
				section.style.display = 'none';
			}
		});
		withAddedRemoved(function (section) {
			var added = section.getAttribute('data-love-version-added');
			var removed = section.getAttribute('data-love-version-removed');
			if (compareVersions(added, removed) && compareVersions(installed, added)) {
				section.style.display = null;
			}
		});
	}

	function filterAll (hideOrShowNotes) {
		hideOrShowNotes();
		withSections(function (section) { section.style.display = null });
	}

	function filterLatest () {
		filterAll(hideNotes);
		withRemoved(function (section) { section.style.display = 'none' });
		withAddedRemoved(function (section) {
			var added = section.getAttribute('data-love-version-added');
			var removed = section.getAttribute('data-love-version-removed');
			if (compareVersions(added, removed)) {
				section.style.display = null;
			}
		});
	}

	function applyFilter (value) {
		storeValue('versionpicker-version', value);
		if (value == 'all') {
			filterAll(showNotes);
			return;
		}
		if (value == 'latest') {
			filterLatest();
			return;
		}
		filterVersion(value);
	}

	function injectFilterPicker () {
		var target = document.getElementById('ca-nstab-main').parentNode;

		picker.style.position = 'absolute';
		picker.style.right = 0;
		picker.style.margin = '0.25rem';
		picker.style.padding = '0.15rem';

		target.parentNode.insertBefore(picker, target);
	}

	function injectVersionTag (number, name) {
		injectPickerOption(number, 'Version ' + number + ': ' + name);
	}

	function injectVersionTags () {
		var versions = [
			{"version": "11.5", "codename": "Mysterious Mysteries"},
			{"version": "11.4", "codename": "Mysterious Mysteries"},
			{"version": "11.3", "codename": "Mysterious Mysteries"},
			{"version": "11.2", "codename": "Mysterious Mysteries"},
			{"version": "11.1", "codename": "Mysterious Mysteries"},
			{"version": "11.0", "codename": "Mysterious Mysteries"},
			{"version": "0.10.2", "codename": "Super Toast"},
			{"version": "0.10.1", "codename": "Super Toast"},
			{"version": "0.10.0", "codename": "Super Toast"},
			{"version": "0.9.2", "codename": "Baby Inspector"},
			{"version": "0.9.1", "codename": "Baby Inspector"},
			{"version": "0.9.0", "codename": "Baby Inspector"},
			{"version": "0.8.0", "codename": "Rubber Piggy"},
			{"version": "0.7.2", "codename": "Game Slave"},
			{"version": "0.7.1", "codename": "Game Slave"},
			{"version": "0.7.0", "codename": "Game Slave"},
			{"version": "0.6.2", "codename": "Jiggly Juice"},
			{"version": "0.6.1", "codename": "Jiggly Juice"},
			{"version": "0.6.0", "codename": "Jiggly Juice"},
			{"version": "0.5.0", "codename": "Salted Nuts"},
			{"version": "0.4.0", "codename": "Taco Beam"},
			{"version": "0.3.2", "codename": "Lemony Fresh"},
			{"version": "0.3.1", "codename": "Space Meat"},
			{"version": "0.3.0", "codename": "Mutant Vermin"},
			{"version": "0.2.1", "codename": "Impending Doom"},
			{"version": "0.2.0", "codename": "Mini Moose"},
			{"version": "0.1.1", "codename": "Santa Power"}
		]

		for (var i = 0; i < versions.length; i++) {
			injectVersionTag(versions[i].version, versions[i].codename);
		}
	}

	function setPicker (target) {
		for (var i = 0; i < picker.options.length; ++i) {
			if (picker.options[i].value === target) {
				picker.selectedIndex = i;
				picker.onchange();
				break;
			}
		}
	}

	function main () {
		wrapSections();
		scanSections();
		scanTables();
		injectPickerOption('all', 'All Versions');
		injectPickerOption('latest', 'Latest Version');
		injectVersionTags();
		injectFilterPicker();
		var target = retrieveValue('versionpicker-version');
		if (target !== undefined) {
			setPicker(target);
		}
	}

	main();
}

versionpicker();