https://www.gemeindeentwicklung.at/typo3conf/ext/gowest_theme/Reso…/Dist/cssrelpreload.js?1596109846

1/*! loadCSS. [c]2017 Filament Group, Inc. MIT License */
2/* This file is meant as a standalone workflow for
3- testing support for link[rel=preload]
4- enabling async CSS loading in browsers that do not support rel=preload
5- applying rel preload css once loaded, whether supported or not.
6*/
7(function( w ){
8	"use strict";
9	// rel=preload support test
10	if( !w.loadCSS ){
11		w.loadCSS = function(){};
12	}
13	// define on the loadCSS obj
14	var rp = loadCSS.relpreload = {};
15	// rel=preload feature support test
16	// runs once and returns a function for compat purposes
17	rp.support = (function(){
18		var ret;
19		try {
20			ret = w.document.createElement( "link" ).relList.supports( "preload" ); 
21		} catch (e) {
22			ret = false;
23		}
24		return function(){
25			return ret;
26		};
27	})();
28
29	// if preload isn't supported, get an asynchronous load by using a non-matching media attribute
30	// then change that media back to its intended value on load
31	rp.bindMediaToggle = function( link ){
32		// remember existing media attr for ultimate state, or default to 'all'
33		var finalMedia = link.media || "all";
34
35		function enableStylesheet(){
36			// unbind listeners
37			if( link.addEventListener ){
38				link.removeEventListener( "load", enableStylesheet );
39			} else if( link.attachEvent ){
40				link.detachEvent( "onload", enableStylesheet );
41			}
42			link.setAttribute( "onload", null ); 
43			link.media = finalMedia;
44		}
45
46		// bind load handlers to enable media
47		if( link.addEventListener ){
48			link.addEventListener( "load", enableStylesheet );
49		} else if( link.attachEvent ){
50			link.attachEvent( "onload", enableStylesheet );
51		}
52
53		// Set rel and non-applicable media type to start an async request
54		// note: timeout allows this to happen async to let rendering continue in IE
55		setTimeout(function(){
56			link.rel = "stylesheet";
57			link.media = "only x";
58		});
59	};
60
61	// loop through link elements in DOM
62	rp.poly = function(){
63		// double check this to prevent external calls from running
64		if( rp.support() ){
65			return;
66		}
67		var links = w.document.getElementsByTagName( "link" );
68		for( var i = 0; i < links.length; i++ ){
69			var link = links[ i ];
70			// qualify links to those with rel=preload and as=style attrs
71			if( link.rel === "preload" && link.getAttribute( "as" ) === "style" && !link.getAttribute( "data-loadcss" ) ){
72				// prevent rerunning on link
73				link.setAttribute( "data-loadcss", true );
74				// bind listeners to toggle media back
75				rp.bindMediaToggle( link );
76			}
77		}
78	};
79
80	// if unsupported, run the polyfill
81	if( !rp.support() ){
82		// run once at least
83		rp.poly();
84
85		// rerun poly on an interval until onload
86		var run = w.setInterval( rp.poly, 500 );
87		if( w.addEventListener ){
88			w.addEventListener( "load", function(){
89				rp.poly();
90				w.clearInterval( run );
91			} );
92		} else if( w.attachEvent ){
93			w.attachEvent( "onload", function(){
94				rp.poly();
95				w.clearInterval( run );
96			} );
97		}
98	}
99
100
101	// commonjs
102	if( typeof exports !== "undefined" ){
103		exports.loadCSS = loadCSS;
104	}
105	else {
106		w.loadCSS = loadCSS;
107	}
108}( typeof global !== "undefined" ? global : this ) );