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critical-foft-preload-polyfill.html
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critical-foft-preload-polyfill.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Critical FOFT with preload (polyfill)</title>
<link rel="preload" href="font-lato/lato-zachleat-optimized.woff2" as="font" type="font/woff2" crossorigin>
<style>
@font-face {
font-family: LatoSubset;
src: url('font-lato/lato-zachleat-optimized.woff2') format('woff2'),
url('font-lato/lato-zachleat-optimized.woff') format('woff');
unicode-range: U+65-90, U+97-122;
}
@font-face {
font-family: Lato;
src: url('font-lato/lato-regular-webfont.woff2') format('woff2'),
url('font-lato/lato-regular-webfont.woff') format('woff');
}
@font-face {
font-family: LatoBold;
src: url('font-lato/lato-bold-webfont.woff2') format('woff2'),
url('font-lato/lato-bold-webfont.woff') format('woff');
font-weight: 700;
}
@font-face {
font-family: LatoItalic;
src: url('font-lato/lato-italic-webfont.woff2') format('woff2'),
url('font-lato/lato-italic-webfont.woff') format('woff');
font-style: italic;
}
@font-face {
font-family: LatoBoldItalic;
src: url('font-lato/lato-bolditalic-webfont.woff2') format('woff2'),
url('font-lato/lato-bolditalic-webfont.woff') format('woff');
font-weight: 700;
font-style: italic;
}
body {
font-family: sans-serif;
}
.fonts-stage-1 body {
font-family: LatoSubset, sans-serif;
font-weight: 400;
font-style: normal;
}
.fonts-stage-2 body {
font-family: Lato, sans-serif;
}
.fonts-stage-2 h1,
.fonts-stage-2 strong {
font-family: LatoBold, sans-serif;
font-weight: 700;
}
.fonts-stage-2 em {
font-family: LatoItalic, sans-serif;
font-style: italic;
}
.fonts-stage-2 strong em,
.fonts-stage-2 em strong {
font-family: LatoBoldItalic, sans-serif;
font-weight: 700;
font-style: italic;
}
</style>
<script>
(function() {
// Optimization for Repeat Views
if( sessionStorage.fontsLoadedCriticalFoftPreloadPolyfill ) {
document.documentElement.className += " fonts-stage-2";
return;
}
/* Font Face Observer v2.0.13 - © Bram Stein. License: BSD-3-Clause */
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(function(){function l(a,b){document.addEventListener?a.addEventListener("scroll",b,!1):a.attachEvent("scroll",b)}function m(a){document.body?a():document.addEventListener?document.addEventListener("DOMContentLoaded",function c(){document.removeEventListener("DOMContentLoaded",c);a()}):document.attachEvent("onreadystatechange",function k(){if("interactive"==document.readyState||"complete"==document.readyState)document.detachEvent("onreadystatechange",k),a()})};function r(a){this.a=document.createElement("div");this.a.setAttribute("aria-hidden","true");this.a.appendChild(document.createTextNode(a));this.b=document.createElement("span");this.c=document.createElement("span");this.h=document.createElement("span");this.f=document.createElement("span");this.g=-1;this.b.style.cssText="max-width:none;display:inline-block;position:absolute;height:100%;width:100%;overflow:scroll;font-size:16px;";this.c.style.cssText="max-width:none;display:inline-block;position:absolute;height:100%;width:100%;overflow:scroll;font-size:16px;";
this.f.style.cssText="max-width:none;display:inline-block;position:absolute;height:100%;width:100%;overflow:scroll;font-size:16px;";this.h.style.cssText="display:inline-block;width:200%;height:200%;font-size:16px;max-width:none;";this.b.appendChild(this.h);this.c.appendChild(this.f);this.a.appendChild(this.b);this.a.appendChild(this.c)}
function t(a,b){a.a.style.cssText="max-width:none;min-width:20px;min-height:20px;display:inline-block;overflow:hidden;position:absolute;width:auto;margin:0;padding:0;top:-999px;white-space:nowrap;font-synthesis:none;font:"+b+";"}function y(a){var b=a.a.offsetWidth,c=b+100;a.f.style.width=c+"px";a.c.scrollLeft=c;a.b.scrollLeft=a.b.scrollWidth+100;return a.g!==b?(a.g=b,!0):!1}function z(a,b){function c(){var a=k;y(a)&&a.a.parentNode&&b(a.g)}var k=a;l(a.b,c);l(a.c,c);y(a)};function A(a,b){var c=b||{};this.family=a;this.style=c.style||"normal";this.weight=c.weight||"normal";this.stretch=c.stretch||"normal"}var B=null,C=null,E=null,F=null;function G(){if(null===C)if(J()&&/Apple/.test(window.navigator.vendor)){var a=/AppleWebKit\/([0-9]+)(?:\.([0-9]+))(?:\.([0-9]+))/.exec(window.navigator.userAgent);C=!!a&&603>parseInt(a[1],10)}else C=!1;return C}function J(){null===F&&(F=!!document.fonts);return F}
function K(){if(null===E){var a=document.createElement("div");try{a.style.font="condensed 100px sans-serif"}catch(b){}E=""!==a.style.font}return E}function L(a,b){return[a.style,a.weight,K()?a.stretch:"","100px",b].join(" ")}
A.prototype.load=function(a,b){var c=this,k=a||"BESbswy",q=0,D=b||3E3,H=(new Date).getTime();return new Promise(function(a,b){if(J()&&!G()){var M=new Promise(function(a,b){function e(){(new Date).getTime()-H>=D?b():document.fonts.load(L(c,'"'+c.family+'"'),k).then(function(c){1<=c.length?a():setTimeout(e,25)},function(){b()})}e()}),N=new Promise(function(a,c){q=setTimeout(c,D)});Promise.race([N,M]).then(function(){clearTimeout(q);a(c)},function(){b(c)})}else m(function(){function u(){var b;if(b=-1!=
f&&-1!=g||-1!=f&&-1!=h||-1!=g&&-1!=h)(b=f!=g&&f!=h&&g!=h)||(null===B&&(b=/AppleWebKit\/([0-9]+)(?:\.([0-9]+))/.exec(window.navigator.userAgent),B=!!b&&(536>parseInt(b[1],10)||536===parseInt(b[1],10)&&11>=parseInt(b[2],10))),b=B&&(f==v&&g==v&&h==v||f==w&&g==w&&h==w||f==x&&g==x&&h==x)),b=!b;b&&(d.parentNode&&d.parentNode.removeChild(d),clearTimeout(q),a(c))}function I(){if((new Date).getTime()-H>=D)d.parentNode&&d.parentNode.removeChild(d),b(c);else{var a=document.hidden;if(!0===a||void 0===a)f=e.a.offsetWidth,
g=n.a.offsetWidth,h=p.a.offsetWidth,u();q=setTimeout(I,50)}}var e=new r(k),n=new r(k),p=new r(k),f=-1,g=-1,h=-1,v=-1,w=-1,x=-1,d=document.createElement("div");d.dir="ltr";t(e,L(c,"sans-serif"));t(n,L(c,"serif"));t(p,L(c,"monospace"));d.appendChild(e.a);d.appendChild(n.a);d.appendChild(p.a);document.body.appendChild(d);v=e.a.offsetWidth;w=n.a.offsetWidth;x=p.a.offsetWidth;I();z(e,function(a){f=a;u()});t(e,L(c,'"'+c.family+'",sans-serif'));z(n,function(a){g=a;u()});t(n,L(c,'"'+c.family+'",serif'));
z(p,function(a){h=a;u()});t(p,L(c,'"'+c.family+'",monospace'))})})};"object"===typeof module?module.exports=A:(window.FontFaceObserver=A,window.FontFaceObserver.prototype.load=A.prototype.load);}());
var fontASubset = new FontFaceObserver('LatoSubset');
Promise.all([fontASubset.load(null, 10000)]).then(function () {
document.documentElement.className += " fonts-stage-1";
var fontA = new FontFaceObserver('Lato');
var fontB = new FontFaceObserver('LatoBold', {
weight: 700
});
var fontC = new FontFaceObserver('LatoItalic', {
style: 'italic'
});
var fontD = new FontFaceObserver('LatoBoldItalic', {
weight: 700,
style: 'italic'
});
Promise.all([
fontA.load(null, 10000),
fontB.load(null, 10000),
fontC.load(null, 10000),
fontD.load(null, 10000)
]).then(function() {
document.documentElement.className += " fonts-stage-2";
// Optimization for Repeat Views
sessionStorage.fontsLoadedCriticalFoftPreloadPolyfill = true;
});
});
})();
</script>
</head>
<body>
<h1>Critical FOFT with preload (polyfill)</h1>
<p>This is a paragraph. <strong>This is heavier text.</strong> <em>This is emphasized text.</em> <strong><em>This is heavier and emphasized text.</em></strong></p>
<hr style="margin-top: 2em">
<ul>
<li>This demo is a companion to <a href="https://www.zachleat.com/web/comprehensive-webfonts/">A Comprehensive Guide to Font Loading Strategies</a></li>
<li>See all demos on <a href="https://github.com/zachleat/web-font-loading-recipes">GitHub <code>zachleat/web-font-loading-recipes</code></a></li>
</ul>
</body>
</html>