respond.src.js

/*
 * respond.js - A small and fast polyfill for min/max-width CSS3 Media Queries
 * Copyright 2011, Scott Jehl, scottjehl.com
 * Dual licensed under the MIT or GPL Version 2 licenses.
 * Usage: Check out the readme file or github.com/scottjehl/respond
*/
(function( win, mqSupported ){
	//exposed namespace
	win.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	= mqSupported;

	//if media queries are supported, exit here
	if( mqSupported ){ return; }

	//define vars
	var doc 			= win.document,
		docElem 		= doc.documentElement,
		mediastyles		= [],
		rules			= [],
		appendedEls 	= [],
		parsedSheets 	= {},
		resizeThrottle	= 30,
		head 			= doc.getElementsByTagName( "head" )[0] || docElem,
		links			= head.getElementsByTagName( "link" ),
		requestQueue	= [],

		//loop stylesheets, send text content to translate
		ripCSS			= function(){
			var sheets 	= links,
				sl 		= sheets.length;

			for( var i = 0; i < sl; i++ ){
				var sheet		= sheets[ 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 ] ){
					if( !/^([a-zA-Z]+?:(\/\/)?(www\.)?)/.test( href )
						|| href.replace( RegExp.$1, "" ).split( "/" )[0] === win.location.host ){
						requestQueue.push( {
							href: href,
							media: media
						} );
					}
					else{
						parsedSheets[ href ] = true;
					}
				}
			}
			makeRequests();

		},

		//recurse through request queue, get css text
		makeRequests	= function(){
			if( requestQueue.length ){
				var thisRequest = requestQueue.shift();

				jQuery.get( thisRequest.href, function( styles ){
					translate( styles, thisRequest.href, thisRequest.media );
					parsedSheets[ thisRequest.href ] = true;
					makeRequests();
				} );
			}
		},

		//find media blocks in css text, convert to style blocks
		translate		= function( styles, href, media ){
			var qs		= styles.match( /@media ([^\{]+)\{([\S\s]+?)(?=\}\/\*\/mediaquery\*\/)/gmi ),
				ql		= qs && qs.length || 0,
				//try to get CSS path
				href	= href.substring( 0, href.lastIndexOf( "/" )),
				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;

				//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 ) );
				}

				var eachq	= fullq.split( "," ),
					eql		= eachq.length;

				for( var j = 0; j < eql; j++ ){
					var thisq	= eachq[ j ];
					mediastyles.push( {
						media	: thisq.match( /(only\s+)?([a-zA-Z]+)(\sand)?/ ) && RegExp.$2,
						rules	: rules.length - 1,
						minw	: thisq.match( /\(min\-width:\s?(\s?[0-9]+)px\s?\)/ ) && parseFloat( RegExp.$1 ),
						maxw	: thisq.match( /\(max\-width:\s?(\s?[0-9]+)px\s?\)/ ) && parseFloat( RegExp.$1 )
					} );
				}
			}

			applyMedia();
		},

		lastCall,

		resizeDefer,

		//enable/disable styles
		applyMedia			= function( fromResize ){
			var name		= "clientWidth",
				docElemProp	= docElem[ name ],
				currWidth 	= doc.compatMode === "CSS1Compat" && docElemProp || doc.body[ name ] || docElemProp,
				styleBlocks	= {},
				dFrag		= doc.createDocumentFragment(),
				lastLink	= links[ links.length-1 ],
				now 		= (new Date()).getTime();

			//throttle resize calls
			if( fromResize && lastCall && now - lastCall < resizeThrottle ){
				clearTimeout( resizeDefer );
				resizeDefer = setTimeout( applyMedia, resizeThrottle );
				return;
			}
			else {
				lastCall	= now;
			}

			for( var i in mediastyles ){
				var thisstyle = mediastyles[ i ];
				if( !thisstyle.minw && !thisstyle.maxw ||
					( !thisstyle.minw || thisstyle.minw && currWidth >= thisstyle.minw ) &&
					(!thisstyle.maxw || thisstyle.maxw && currWidth <= thisstyle.maxw ) ){
						if( !styleBlocks[ thisstyle.media ] ){
							styleBlocks[ thisstyle.media ] = [];
						}
						styleBlocks[ thisstyle.media ].push( rules[ thisstyle.rules ] );
				}
			}

			//remove any existing respond style element(s)
			for( var i in appendedEls ){
				if( appendedEls[ i ] && appendedEls[ i ].parentNode === head ){
					head.removeChild( appendedEls[ i ] );
				}
			}

			//inject active styles, grouped by media type
			for( var i in styleBlocks ){
				var ss		= doc.createElement( "style" ),
					css		= styleBlocks[ i ].join( "\n" );

				ss.type = "text/css";
				ss.media	= i;

				if ( ss.styleSheet ){
		        	ss.styleSheet.cssText = css;
		        }
		        else {
					ss.appendChild( doc.createTextNode( css ) );
		        }
		        dFrag.appendChild( ss );
				appendedEls.push( ss );
			}

			//append to DOM at once
			head.insertBefore( dFrag, lastLink.nextSibling );
		};

	//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,
	(function( win ){

		//for speed, flag browsers with window.matchMedia support and IE 9 as supported
		if( win.matchMedia ){ return true; }

		var bool,
			doc			= document,
			docElem		= doc.documentElement,
			refNode		= docElem.firstElementChild || docElem.firstChild,
			// fakeBody required for <FF4 when executed in <head>
			fakeBody	= doc.createElement( "body" ),
			div			= doc.createElement( "div" ),
			q			= "only all";

		div.id = "mq-test-1";
		div.style.cssText = "position:absolute;top:-99em";
		fakeBody.appendChild( div );

		div.innerHTML = '_<style media="'+q+'"> #mq-test-1 { width: 9px; }</style>';
		docElem.insertBefore( fakeBody, refNode );
		div.removeChild( div.firstChild );
		bool = div.offsetWidth == 9;
		docElem.removeChild( fakeBody );
		return bool;
	})( this )
);