https://housely.com/wp-content/themes/bimber/js/matchmedia/matchmedia.addlistener.js

1/*! matchMedia() polyfill addListener/removeListener extension. Author & copyright (c) 2012: Scott Jehl. Dual MIT/BSD license */
2(function(){
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);
16
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;
22
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;
27
28                        for (var j = 0, jl = listeners.length; j < jl; j++) {
29                            listeners[j].call(window, mql);
30                        }
31                    }
32                }
33            }, 30);
34        };
35
36    window.matchMedia = function(media) {
37        var mql         = localMatchMedia(media),
38            listeners   = [],
39            index       = 0;
40
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            }
46
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            }
53
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            }
61
62            listeners.push(listener);
63        };
64
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);
69                }
70            }
71        };
72
73        return mql;
74    };
75}());