respond.src.js 9.52 KB

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/*! 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 */

window.matchMedia = window.matchMedia || (function( doc, undefined ) {

  "use strict";

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

  div.id = "mq-test-1";
  div.style.cssText = "position:absolute;top:-100em";
  fakeBody.style.background = "none";
  fakeBody.appendChild(div);

  return function(q){

    div.innerHTML = "&shy;<style media=\"" + q + "\"> #mq-test-1 { width: 42px; }</style>";

    docElem.insertBefore( fakeBody, refNode );
    bool = div.offsetWidth === 42;
    docElem.removeChild( fakeBody );

    return {
      matches: bool,
      media: q
    };

  };

}( document ));


/*! 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);