IE低版本支持html5+css3的必备文件

/* Respond.js: min/max-width media query polyfill. (c) Scott Jehl. MIT Lic. j.mp/respondjs */ (function( w ){ "use strict"; //exposed namespace var respond = {}; w.respond = respond; //define update even in native-mq-supporting browsers, to avoid errors respond.update = function(){}; //define ajax obj var requestQueue = [], xmlHttp = (function() { var xmlhttpmethod = false; try { xmlhttpmethod = new w.XMLHttpRequest(); } catch( e ){ xmlhttpmethod = new w.ActiveXObject( "Microsoft.XMLHTTP" ); } return function(){ return xmlhttpmethod; }; })(), //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 ); }, isUnsupportedMediaQuery = function( query ) { return query.replace( respond.regex.minmaxwh, '' ).match( respond.regex.other ); }; //expose for testing respond.ajax = ajax; respond.queue = requestQueue; respond.unsupportedmq = isUnsupportedMediaQuery; respond.regex = { media: /@media[^\{]+\{([^\{\}]*\{[^\}\{]*\})+/gi, keyframes: /@(?:\-(?:o|moz|webkit)\-)?keyframes[^\{]+\{(?:[^\{\}]*\{[^\}\{]*\})+[^\}]*\}/gi, comments: /\/\*[^*]*\*+([^/][^*]*\*+)*\//gi, urls: /(url\()['"]?([^\/\)'"][^:\)'"]+)['"]?(\))/g, findStyles: /@media *([^\{]+)\{([\S\s]+?)$/, only: /(only\s+)?([a-zA-Z]+)\s?/, minw: /\(\s*min\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/, maxw: /\(\s*max\-width\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/, minmaxwh: /\(\s*m(in|ax)\-(height|width)\s*:\s*(\s*[0-9\.]+)(px|em)\s*\)/gi, other: /\([^\)]*\)/g }; //expose media query support flag for external use respond.mediaQueriesSupported = w.matchMedia && w.matchMedia( "only all" ) !== null && w.matchMedia( "only all" ).matches; //if media queries are supported, exit here if( respond.mediaQueriesSupported ){ return; } //define vars var doc = w.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" ), lastCall, resizeDefer, //cached container for 1em value, populated the first time it's needed eminpx, // returns the value of 1em in pixels getEmValue = function() { var ret, div = doc.createElement('div'), body = doc.body, originalHTMLFontSize = docElem.style.fontSize, originalBodyFontSize = body && body.style.fontSize, fakeUsed = false; div.style.cssText = "position:absolute;font-size:1em;width:1em"; if( !body ){ body = fakeUsed = doc.createElement( "body" ); body.style.background = "none"; } // 1em in a media query is the value of the default font size of the browser // reset docElem and body to ensure the correct value is returned docElem.style.fontSize = "100%"; body.style.fontSize = "100%"; body.appendChild( div ); if( fakeUsed ){ docElem.insertBefore( body, docElem.firstChild ); } ret = div.offsetWidth; if( fakeUsed ){ docElem.removeChild( body ); } else { body.removeChild( div ); } // restore the original values docElem.style.fontSize = originalHTMLFontSize; if( originalBodyFontSize ) { body.style.fontSize = originalBodyFontSize; } //also update eminpx before returning ret = eminpx = parseFloat(ret); return ret; }, //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 ){ w.clearTimeout( resizeDefer ); resizeDefer = w.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 ] ); } } } appendedEls.length = 0; //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 ); } } }, //find media blocks in css text, convert to style blocks translate = function( styles, href, media ){ var qs = styles.replace( respond.regex.comments, '' ) .replace( respond.regex.keyframes, '' ) .match( respond.regex.media ), ql = qs && qs.length || 0; //try to get CSS path href = href.substring( 0, href.lastIndexOf( "/" ) ); var repUrls = function( css ){ return css.replace( respond.regex.urls, "$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( respond.regex.findStyles ) && 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 ]; if( isUnsupportedMediaQuery( thisq ) ) { continue; } mediastyles.push( { media : thisq.split( "(" )[ 0 ].match( respond.regex.only ) && RegExp.$2 || "all", rules : rules.length - 1, hasquery : thisq.indexOf("(") > -1, minw