The ultimate repond.js script w/ match media and addListener polyfills

Respond.js with match media & addListener

/*! matchMedia() polyfill - Test a CSS media type/query in JS. Authors & copyright (c) 2012: Scott Jehl, Paul Irish, Nicholas Zakas. Dual MIT/BSD license */
/*! NOTE: If you're already including a window.matchMedia polyfill via Modernizr or otherwise, you don't need this part */
/*! matchMedia() polyfill - Test a CSS media type/query in JS. Authors & copyright (c) 2012: Scott Jehl, Paul Irish, Nicholas Zakas, David Knight. Dual MIT/BSD license */


// Paul Irish's match media: https://github.com/paulirish/matchMedia.js/blob/master/matchMedia.js
window.matchMedia || (window.matchMedia = function() {
    "use strict";

    // For browsers that support matchMedium api such as IE 9 and webkit
    var styleMedia = (window.styleMedia || window.media);

    // For those that don't support matchMedium
    if (!styleMedia) {
        var style       = document.createElement('style'),
            script      = document.getElementsByTagName('script')[0],
            info        = null;

        style.type  = 'text/css';
        style.id    = 'matchmediajs-test';

        script.parentNode.insertBefore(style, script);

        // 'style.currentStyle' is used by IE <= 8 and 'window.getComputedStyle' for all other browsers
        info = ('getComputedStyle' in window) && window.getComputedStyle(style) || style.currentStyle;

        styleMedia = {
            matchMedium: function(media) {
                var text = '@media ' + media + '{ #matchmediajs-test { width: 1px; } }';

                // 'style.styleSheet' is used by IE <= 8 and 'style.textContent' for all other browsers
                if (style.styleSheet) {
                    style.styleSheet.cssText = text;
                } else {
                    style.textContent = text;
                }

                // Test if media query is true or false
                return info.width === '1px';
            }
        };
    }

    return function(media) {
        return {
            matches: styleMedia.matchMedium(media || 'all'),
            media: media || 'all'
        };
    };
}());

// Paul Irish's addListener polyfill: https://github.com/paulirish/matchMedia.js/blob/master/matchMedia.addListener.js

/*! matchMedia() polyfill addListener/removeListener extension. Author & copyright (c) 2012: Scott Jehl. Dual MIT/BSD license */
(function(){
    // Bail out for browsers that have addListener support
    if (window.matchMedia && window.matchMedia('all').addListener) {
        return false;
    }

    var localMatchMedia = window.matchMedia,
        hasMediaQueries = localMatchMedia('only all').matches,
        isListening     = false,
        timeoutID       = 0,    // setTimeout for debouncing 'handleChange'
        queries         = [],   // Contains each 'mql' and associated 'listeners' if 'addListener' is used
        handleChange    = function(evt) {
            // Debounce
            clearTimeout(timeoutID);

            timeoutID = setTimeout(function() {
                for (var i = 0, il = queries.length; i < il; i++) {
                    var mql         = queries[i].mql,
                        listeners   = queries[i].listeners || [],
                        matches     = localMatchMedia(mql.media).matches;

                    // Update mql.matches value and call listeners
                    // Fire listeners only if transitioning to or from matched state
                    if (matches !== mql.matches) {
                        mql.matches = matches;

                        for (var j = 0, jl = listeners.length; j < jl; j++) {
                            listeners[j].call(window, mql);
                        }
                    }
                }
            }, 30);
        };

    window.matchMedia = function(media) {
        var mql         = localMatchMedia(media),
            listeners   = [],
            index       = 0;

        mql.addListener = function(listener) {
            // Changes would not occur to css media type so return now (Affects IE <= 8)
            if (!hasMediaQueries) {
                return;
            }

            // Set up 'resize' listener for browsers that support CSS3 media queries (Not for IE <= 8)
            // There should only ever be 1 resize listener running for performance
            if (!isListening) {
                isListening = true;
                window.addEventListener('resize', handleChange, true);
            }

            // Push object only if it has not been pushed already
            if (index === 0) {
                index = queries.push({
                    mql         : mql,
                    listeners   : listeners
                });
            }

            listeners.push(listener);
        };

        mql.removeListener = function(listener) {
            for (var i = 0, il = listeners.length; i < il; i++){
                if (listeners[i] === listener){
                    listeners.splice(i, 1);
                }
            }
        };

        return mql;
    };
}());



/*! Respond.js v1.3.0: min/max-width media query polyfill. (c) Scott Jehl. MIT/GPLv2 Lic. j.mp/respondjs  */
(function( win ){

	"use strict";

	//exposed namespace
	var respond = {};
	win.respond = respond;
	
	//define update even in native-mq-supporting browsers, to avoid errors
	respond.update = function(){};
	
	//expose media query support flag for external use
	respond.mediaQueriesSupported	= win.matchMedia && win.matchMedia( "only all" ).matches;
	
	//if media queries are supported, exit here
	if( respond.mediaQueriesSupported ){
		return;
	}
	
	//define vars
	var doc = win.document,
		docElem = doc.documentElement,
		mediastyles = [],
		rules = [],
		appendedEls = [],
		parsedSheets = {},
		resizeThrottle = 30,
		head = doc.getElementsByTagName( "head" )[0] || docElem,
		base = doc.getElementsByTagName( "base" )[0],
		links = head.getElementsByTagName( "link" ),
		requestQueue = [],
		
		//loop stylesheets, send text content to translate
		ripCSS = function(){

			for( var i = 0; i < links.length; i++ ){
				var sheet = links[ i ],
				href = sheet.href,
				media = sheet.media,
				isCSS = sheet.rel && sheet.rel.toLowerCase() === "stylesheet";

				//only links plz and prevent re-parsing
				if( !!href && isCSS && !parsedSheets[ href ] ){
					// selectivizr exposes css through the rawCssText expando
					if (sheet.styleSheet && sheet.styleSheet.rawCssText) {
						translate( sheet.styleSheet.rawCssText, href, media );
						parsedSheets[ href ] = true;
					} else {
						if( (!/^([a-zA-Z:]*\/\/)/.test( href ) && !base) ||
							href.replace( RegExp.$1, "" ).split( "/" )[0] === win.location.host ){
							requestQueue.push( {
								href: href,
								media: media
							} );
						}
					}
				}
			}
			makeRequests();
		},
		
		//recurse through request queue, get css text
		makeRequests	= function(){
			if( requestQueue.length ){
				var thisRequest = requestQueue.shift();
				
				ajax( thisRequest.href, function( styles ){
					translate( styles, thisRequest.href, thisRequest.media );
					parsedSheets[ thisRequest.href ] = true;

					// by wrapping recursive function call in setTimeout 
					// we prevent "Stack overflow" error in IE7
					win.setTimeout(function(){ makeRequests(); },0);
				} );
			}
		},
		
		//find media blocks in css text, convert to style blocks
		translate = function( styles, href, media ){
			var qs = styles.match(  /@media[^\{]+\{([^\{\}]*\{[^\}\{]*\})+/gi ),
				ql = qs && qs.length || 0;

			//try to get CSS path
			href = href.substring( 0, href.lastIndexOf( "/" ) );

			var repUrls	= function( css ){
					return css.replace( /(url\()['"]?([^\/\)'"][^:\)'"]+)['"]?(\))/g, "$1" + href + "$2$3" );
				},
				useMedia = !ql && media;

			//if path exists, tack on trailing slash
			if( href.length ){ href += "/"; }	
				
			//if no internal queries exist, but media attr does, use that	
			//note: this currently lacks support for situations where a media attr is specified on a link AND
				//its associated stylesheet has internal CSS media queries.
				//In those cases, the media attribute will currently be ignored.
			if( useMedia ){
				ql = 1;
			}

			for( var i = 0; i < ql; i++ ){
				var fullq, thisq, eachq, eql;

				//media attr
				if( useMedia ){
					fullq = media;
					rules.push( repUrls( styles ) );
				}
				//parse for styles
				else{
					fullq = qs[ i ].match( /@media *([^\{]+)\{([\S\s]+?)$/ ) && RegExp.$1;
					rules.push( RegExp.$2 && repUrls( RegExp.$2 ) );
				}
				
				eachq = fullq.split( "," );
				eql	= eachq.length;
					
				for( var j = 0; j < eql; j++ ){
					thisq = eachq[ j ];
					mediastyles.push( { 
						media : thisq.split( "(" )[ 0 ].match( /(only\s+)?([a-zA-Z]+)\s?/ ) && RegExp.$2 || "all",
						rules : rules.length - 1,
						hasquery : thisq.indexOf("(") > -1,
						minw : thisq.match( /\(\s*min\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/ ) && parseFloat( RegExp.$1 ) + ( RegExp.$2 || "" ), 
						maxw : thisq.match( /\(\s*max\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/ ) && parseFloat( RegExp.$1 ) + ( RegExp.$2 || "" )
					} );
				}	
			}

			applyMedia();
		},
        
		lastCall,
		
		resizeDefer,
		
		// returns the value of 1em in pixels
		getEmValue = function() {
			var ret,
				div = doc.createElement('div'),
				body = doc.body,
				fakeUsed = false;
									
			div.style.cssText = "position:absolute;font-size:1em;width:1em";
					
			if( !body ){
				body = fakeUsed = doc.createElement( "body" );
				body.style.background = "none";
			}
					
			body.appendChild( div );
								
			docElem.insertBefore( body, docElem.firstChild );
								
			ret = div.offsetWidth;
								
			if( fakeUsed ){
				docElem.removeChild( body );
			}
			else {
				body.removeChild( div );
			}
			
			//also update eminpx before returning
			ret = eminpx = parseFloat(ret);
								
			return ret;
		},
		
		//cached container for 1em value, populated the first time it's needed 
		eminpx,
		
		//enable/disable styles
		applyMedia = function( fromResize ){
			var name = "clientWidth",
				docElemProp = docElem[ name ],
				currWidth = doc.compatMode === "CSS1Compat" && docElemProp || doc.body[ name ] || docElemProp,
				styleBlocks	= {},
				lastLink = links[ links.length-1 ],
				now = (new Date()).getTime();

			//throttle resize calls	
			if( fromResize && lastCall && now - lastCall < resizeThrottle ){
				win.clearTimeout( resizeDefer );
				resizeDefer = win.setTimeout( applyMedia, resizeThrottle );
				return;
			}
			else {
				lastCall = now;
			}
										
			for( var i in mediastyles ){
				if( mediastyles.hasOwnProperty( i ) ){
					var thisstyle = mediastyles[ i ],
						min = thisstyle.minw,
						max = thisstyle.maxw,
						minnull = min === null,
						maxnull = max === null,
						em = "em";
					
					if( !!min ){
						min = parseFloat( min ) * ( min.indexOf( em ) > -1 ? ( eminpx || getEmValue() ) : 1 );
					}
					if( !!max ){
						max = parseFloat( max ) * ( max.indexOf( em ) > -1 ? ( eminpx || getEmValue() ) : 1 );
					}
					
					// if there's no media query at all (the () part), or min or max is not null, and if either is present, they're true
					if( !thisstyle.hasquery || ( !minnull || !maxnull ) && ( minnull || currWidth >= min ) && ( maxnull || currWidth <= max ) ){
						if( !styleBlocks[ thisstyle.media ] ){
							styleBlocks[ thisstyle.media ] = [];
						}
						styleBlocks[ thisstyle.media ].push( rules[ thisstyle.rules ] );
					}
				}
			}
			
			//remove any existing respond style element(s)
			for( var j in appendedEls ){
				if( appendedEls.hasOwnProperty( j ) ){
					if( appendedEls[ j ] && appendedEls[ j ].parentNode === head ){
						head.removeChild( appendedEls[ j ] );
					}
				}
			}
			
			//inject active styles, grouped by media type
			for( var k in styleBlocks ){
				if( styleBlocks.hasOwnProperty( k ) ){
					var ss = doc.createElement( "style" ),
						css = styleBlocks[ k ].join( "\n" );
					
					ss.type = "text/css";	
					ss.media = k;
					
					//originally, ss was appended to a documentFragment and sheets were appended in bulk.
					//this caused crashes in IE in a number of circumstances, such as when the HTML element had a bg image set, so appending beforehand seems best. Thanks to @dvelyk for the initial research on this one!
					head.insertBefore( ss, lastLink.nextSibling );
					
					if ( ss.styleSheet ){ 
						ss.styleSheet.cssText = css;
					}
					else {
						ss.appendChild( doc.createTextNode( css ) );
					}

					//push to appendedEls to track for later removal
					appendedEls.push( ss );
				}
			}
		},
		//tweaked Ajax functions from Quirksmode
		ajax = function( url, callback ) {
			var req = xmlHttp();
			if (!req){
				return;
			}	
			req.open( "GET", url, true );
			req.onreadystatechange = function () {
				if ( req.readyState !== 4 || req.status !== 200 && req.status !== 304 ){
					return;
				}
				callback( req.responseText );
			};
			if ( req.readyState === 4 ){
				return;
			}
			req.send( null );
		},
		//define ajax obj 
		xmlHttp = (function() {
			var xmlhttpmethod = false;	
			try {
				xmlhttpmethod = new win.XMLHttpRequest();
			}
			catch( e ){
				xmlhttpmethod = new win.ActiveXObject( "Microsoft.XMLHTTP" );
			}
			return function(){
				return xmlhttpmethod;
			};
		})();
	
	//translate CSS
	ripCSS();
	
	//expose update for re-running respond later on
	respond.update = ripCSS;
	
	//adjust on resize
	function callMedia(){
		applyMedia( true );
	}
	if( win.addEventListener ){
		win.addEventListener( "resize", callMedia, false );
	}
	else if( win.attachEvent ){
		win.attachEvent( "onresize", callMedia );
	}
})(this);