<!DOCTYPE html> <meta charset="utf-8"> <link rel="author" title="Myles C. Maxfield" href="mmaxfield@apple.com"> <link rel="help" href="https://drafts.csswg.org/css-font-loading-3/#dom-fontfaceset-add"> <meta name="assert" content="Ensure that calling add() with a CSS-connected FontFace throws." /> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <style> @font-face { font-family: "WebFont"; src: url("resources/Rochester.otf") format("opentype"); } </style> <script> test(function(t) { let font = document.fonts.keys().next().value; let fontFaceSet = new FontFaceSet([]); assert_equals(fontFaceSet.size, 0); assert_throws_dom("InvalidModificationError", function() { fontFaceSet.add(font); }); assert_equals(fontFaceSet.size, 0); let newFont = new FontFace("MyFont", "url('resources/Rochester.otf')"); fontFaceSet.add(newFont); assert_equals(fontFaceSet.size, 1); fontFaceSet.add(newFont); assert_equals(fontFaceSet.size, 1); }); </script> </html>