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/** |
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* Easy Fonts beacon. |
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* |
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* Measures real font usage in the browser and reports decisions to the server: |
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* - which font variants render ABOVE THE FOLD -> preload candidates |
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* - which loaded faces never render anywhere -> unload candidates |
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* |
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* Sources: document.fonts (FontFaceSet) for what loaded, getComputedStyle for |
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* what's actually applied, getBoundingClientRect for above-the-fold. |
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*/ |
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( function () { |
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'use strict'; |
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|
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var CFG = window.EasyFontsBeacon; |
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if ( ! CFG || ! CFG.endpoint || ! document.fonts ) { |
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return; |
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} |
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|
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var GENERIC = /^(serif|sans-serif|monospace|cursive|fantasy|system-ui|ui-(?:serif|sans-serif|monospace|rounded)|-apple-system|blinkmacsystemfont|"?segoe ui"?|helvetica|helvetica neue|arial|times new roman|georgia|courier new|inherit|initial|revert|unset|emoji|math|fangsong)$/i; |
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|
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function clean( name ) { |
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return ( name || '' ).trim().replace( /^["']|["']$/g, '' ); |
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} |
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|
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function normWeight( w ) { |
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if ( w === 'normal' ) { return '400'; } |
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if ( w === 'bold' ) { return '700'; } |
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return String( w || '400' ); |
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} |
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|
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function collect() { |
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var loaded = {}; // family -> { weight: {style:true} } (what the browser fetched) |
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var rendered = {}; // family|weight|style -> true |
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var aboveFold = {};// family|weight|style -> true |
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var foldLine = window.innerHeight || document.documentElement.clientHeight; |
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|
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// 1. Loaded faces. |
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document.fonts.forEach( function ( face ) { |
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if ( face.status !== 'loaded' ) { return; } |
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var fam = clean( face.family ); |
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if ( ! fam || GENERIC.test( fam ) ) { return; } |
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var w = normWeight( face.weight ); |
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var s = face.style || 'normal'; |
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loaded[ fam ] = loaded[ fam ] || {}; |
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loaded[ fam ][ w + '|' + s ] = true; |
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} ); |
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|
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// 2. Rendered + above-the-fold (sample visible text elements). The set |
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// of element types is deliberately broad — a family is only kept on a |
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// page if something here reports it, so missing an element type would |
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// wrongly scope a used font off the page. |
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var nodes = document.querySelectorAll( |
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'h1,h2,h3,h4,h5,h6,p,a,span,li,td,th,caption,button,label,input,textarea,select,option,' + |
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'blockquote,figcaption,figure,dl,dt,dd,summary,details,strong,b,em,i,u,mark,small,' + |
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'cite,q,code,pre,abbr,time,address,legend,output,div' |
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); |
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var max = Math.min( nodes.length, 3000 ); // cap work on huge pages |
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|
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function noteRendered( fam, weight, style, rect ) { |
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if ( ! fam || GENERIC.test( fam ) ) { return; } |
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var key = fam + '|' + normWeight( weight ) + '|' + ( style || 'normal' ); |
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rendered[ key ] = true; |
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if ( rect && rect.top < foldLine && rect.bottom > 0 && rect.width > 0 && rect.height > 0 ) { |
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aboveFold[ key ] = true; |
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} |
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} |
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|
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for ( var i = 0; i < max; i++ ) { |
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var el = nodes[ i ]; |
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|
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var hasText = el.value ? true : ( el.textContent && el.textContent.trim() ); |
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if ( ! hasText ) { continue; } |
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|
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var rect = el.getBoundingClientRect(); |
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var cs = getComputedStyle( el ); |
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noteRendered( clean( ( cs.fontFamily || '' ).split( ',' )[ 0 ] ), cs.fontWeight, cs.fontStyle, rect ); |
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|
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// Generated content (::before / ::after) can carry its own font. |
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var bef = getComputedStyle( el, '::before' ); |
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if ( bef && bef.content && bef.content !== 'none' && bef.content !== 'normal' ) { |
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noteRendered( clean( ( bef.fontFamily || '' ).split( ',' )[ 0 ] ), bef.fontWeight, bef.fontStyle, rect ); |
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} |
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var aft = getComputedStyle( el, '::after' ); |
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if ( aft && aft.content && aft.content !== 'none' && aft.content !== 'normal' ) { |
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noteRendered( clean( ( aft.fontFamily || '' ).split( ',' )[ 0 ] ), aft.fontWeight, aft.fontStyle, rect ); |
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} |
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} |
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|
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// 3. Build decisions. |
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var preload = []; |
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Object.keys( aboveFold ).forEach( function ( key ) { |
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var p = key.split( '|' ); |
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preload.push( { family: p[ 0 ], weight: p[ 1 ], style: p[ 2 ] } ); |
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} ); |
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|
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var unload = []; |
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Object.keys( loaded ).forEach( function ( fam ) { |
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Object.keys( loaded[ fam ] ).forEach( function ( ws ) { |
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var parts = ws.split( '|' ); |
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var key = fam + '|' + parts[ 0 ] + '|' + parts[ 1 ]; |
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if ( ! rendered[ key ] ) { |
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unload.push( { family: fam, weight: parts[ 0 ], style: parts[ 1 ] } ); |
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} |
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} ); |
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} ); |
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|
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var renderedList = Object.keys( rendered ).map( function ( key ) { |
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var p = key.split( '|' ); |
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return { |
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family: p[ 0 ], |
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weight: p[ 1 ], |
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style: p[ 2 ], |
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above_fold: aboveFold[ key ] ? 1 : 0 |
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}; |
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} ); |
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|
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return { rendered: renderedList, preload: preload, unload: unload }; |
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} |
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|
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function send( data ) { |
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if ( ! data.rendered.length && ! data.preload.length ) { return; } |
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|
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var payload = JSON.stringify( { |
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route: CFG.route, |
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device: CFG.device, |
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rendered: data.rendered, |
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preload: data.preload, |
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unload: data.unload |
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} ); |
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|
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var url = CFG.endpoint + '?_wpnonce=' + encodeURIComponent( CFG.nonce ); |
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|
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if ( navigator.sendBeacon ) { |
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navigator.sendBeacon( url, new Blob( [ payload ], { type: 'application/json' } ) ); |
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} else { |
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var xhr = new XMLHttpRequest(); |
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xhr.open( 'POST', url, true ); |
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xhr.setRequestHeader( 'Content-Type', 'application/json' ); |
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xhr.setRequestHeader( 'X-WP-Nonce', CFG.nonce ); |
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xhr.send( payload ); |
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} |
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} |
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|
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// Run after fonts settle, giving lazy/builder fonts time to apply. We also |
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// flush on pagehide/visibilitychange so the report is never lost — important |
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// inside the admin's hidden optimize iframe, which may be torn down quickly. |
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var sent = false; |
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|
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function flush() { |
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if ( sent ) { return; } |
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sent = true; |
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try { send( collect() ); } catch ( e ) {} |
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} |
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|
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document.fonts.ready.then( function () { |
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setTimeout( flush, 1500 ); |
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} ); |
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|
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window.addEventListener( 'pagehide', flush ); |
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document.addEventListener( 'visibilitychange', function () { |
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if ( document.visibilityState === 'hidden' ) { flush(); } |
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} ); |
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}() ); |
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|
