matchMedia.js/matchMedia.addListener.js at master · paulirish/matchMedia.js · GitHub

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1bba387 Added an external extension for addListener and removeListener support i... Scott Jehl authored Aug 3, 2012
		1	/! matchMedia() polyfill addListener/removeListener extension. Author & copyright (c) 2012: Scott Jehl. Dual MIT/BSD license /
		2	(function(){
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		3	// Bail out for browsers that have addListener support
		4	if (window.matchMedia && window.matchMedia('all').addListener) {
		5	return false;
		6	}
		7
		8	var localMatchMedia = window.matchMedia,
		9	hasMediaQueries = localMatchMedia('only all').matches,
		10	isListening = false,
		11	timeoutID = 0, // setTimeout for debouncing 'handleChange'
		12	queries = [], // Contains each 'mql' and associated 'listeners' if 'addListener' is used
		13	handleChange = function(evt) {
		14	// Debounce
		15	clearTimeout(timeoutID);
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		16
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		17	timeoutID = setTimeout(function() {
		18	for (var i = 0, il = queries.length; i < il; i++) {
		19	var mql = queries[i].mql,
		20	listeners = queries[i].listeners \|\| [],
		21	matches = localMatchMedia(mql.media).matches;
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		22
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		23	// Update mql.matches value and call listeners
		24	// Fire listeners only if transitioning to or from matched state
		25	if (matches !== mql.matches) {
		26	mql.matches = matches;
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		27
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		28	for (var j = 0, jl = listeners.length; j < jl; j++) {
		29	listeners[j].call(window, mql);
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		30	}
		31	}
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		32	}
		33	}, 30);
		34	};
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		35
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		36	window.matchMedia = function(media) {
		37	var mql = localMatchMedia(media),
		38	listeners = [],
		39	index = 0;
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		40
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		41	mql.addListener = function(listener) {
		42	// Changes would not occur to css media type so return now (Affects IE <= 8)
		43	if (!hasMediaQueries) {
		44	return;
		45	}
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		46
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		47	// Set up 'resize' listener for browsers that support CSS3 media queries (Not for IE <= 8)
		48	// There should only ever be 1 resize listener running for performance
		49	if (!isListening) {
		50	isListening = true;
		51	window.addEventListener('resize', handleChange, true);
		52	}
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		53
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		54	// Push object only if it has not been pushed already
		55	if (index === 0) {
		56	index = queries.push({
		57	mql : mql,
		58	listeners : listeners
		59	});
		60	}
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		61
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		62	listeners.push(listener);
		63	};
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		64
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		65	mql.removeListener = function(listener) {
		66	for (var i = 0, il = listeners.length; i < il; i++){
		67	if (listeners[i] === listener){
		68	listeners.splice(i, 1);
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		69	}
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		70	}
83ca799 Rewrite of addListener to use window.resize rather than creating 'setInt... knightdr authored Aug 20, 2013
		71	};
0903df1 Restructured initial 'if' statement for clarity knightdr authored Aug 26, 2013
		72
		73	return mql;
		74	};
		75	}());

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