css/css-fonts/font-display/font-display.html

<!DOCTYPE html>
<html class="reftest-wait">
<title>Test for font-display @font-face descriptor</title>
<meta name="timeout" content="long">
<link rel="help" href="https://drafts.csswg.org/css-fonts-4/#font-display-desc">
<link rel="match" href="font-display-ref.html">
<link rel="preload" href="/fonts/Ahem.ttf?pipe=trickle(d0)" as="font" crossorigin>
<style>
.hidden { display: none; }
</style>
<p>Tests how text with a font that takes <i>delay</i> seconds to load look like after <i>T</i> seconds from load start.</p>
<table id="container">
 <tr>
  <th>T[sec]</th>
  <th>delay[sec]</th>
  <th>block</th>
  <th>swap</th>
  <th>fallback</th>
  <th>optional</th>
 </tr>
</table>
<script>
var fontDisplayValues = ['block', 'swap', 'fallback', 'optional'];
var configs = [{time: 0, delay: 1000},
               {time: 1000, delay: 0},
               {time: 1000, delay: 500},
               {time: 1000, delay: 3000},
               {time: 5000, delay: 2000},
               {time: 5000, delay: 4000},
               {time: 5000, delay: 8000}];

function makeFontFaceDeclaration(family, config, display) {
    url = '/fonts/Ahem.ttf?pipe=trickle(d' + config.delay / 1000 + ')';
    return '@font-face { font-family: ' + family + '; src: url("' + url + '"); font-display: ' + display + '; }';
}


var maxTime = Math.max.apply(null, configs.map((config) => config.time));
var table = document.getElementById('container');

window.onload = function() {
    for (var config, i = 0; config = configs[i]; i++) {
        var tr = document.createElement('tr');
        tr.classList.add('hidden');
        var td1 = document.createElement('td');
        td1.textContent = config.time / 1000;
        tr.appendChild(td1);
        var td2 = document.createElement('td');
        td2.textContent = config.delay / 1000;
        tr.appendChild(td2);

        for (var display, j = 0; display = fontDisplayValues[j]; j++) {
            var family = [display, config.time, config.delay].join('-');
            var rule = makeFontFaceDeclaration(family, config, display);
            document.styleSheets[0].insertRule(rule, 0);
            var td = document.createElement('td');
            td.textContent = 'a';
            td.style.fontFamily = family + ', Arial';
            tr.appendChild(td);
        }
        table.appendChild(tr);
        if (config.time == 0) {
            setTimeout((function(tr){
                tr.classList.remove('hidden');
                document.documentElement.classList.remove("reftest-wait");
            }).bind(null, tr), maxTime);
        } else {
            setTimeout((function(tr){tr.classList.remove('hidden')}).bind(null, tr), maxTime - config.time);
        }
    }
}

</script>
</html>