mq-dynamic-empty-children.html (1460B)
1 <!doctype html> 2 <title>Dynamic evaluation of media queries works fine in presence of empty media rule</title> 3 <link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez"> 4 <link rel="author" href="https://mozilla.org" title="Mozilla"> 5 <link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1669600"> 6 <link rel="help" href="https://drafts.csswg.org/mediaqueries-4/"> 7 <script src="/resources/testharness.js"></script> 8 <script src="/resources/testharnessreport.js"></script> 9 <iframe width=500 height=300 frameborder=0></iframe> 10 <script> 11 let iframe = document.querySelector("iframe"); 12 promise_test(async function (t) { 13 await new Promise(resolve => { 14 window.addEventListener("load", resolve); 15 }); 16 let frameLoaded = new Promise(resolve => { 17 iframe.addEventListener("load", resolve); 18 }); 19 iframe.srcdoc = ` 20 <style> 21 :root { background-color: red; } 22 /* This one should never apply */ 23 @media (min-width: 1500px) {} 24 /* This one should change and start matching */ 25 @media (max-width: 400px) { 26 :root { background-color: lime; } 27 } 28 </style> 29 `; 30 await frameLoaded; 31 32 function getColor() { 33 return iframe.contentWindow.getComputedStyle(iframe.contentDocument.documentElement).backgroundColor; 34 } 35 36 assert_equals(getColor(), "rgb(255, 0, 0)", "Should start red"); 37 iframe.width = 400; 38 assert_equals(getColor(), "rgb(0, 255, 0)", "Should turn green"); 39 }); 40 </script>