custom-property-and-allow-discrete.html (2111B)
1 <!doctype html> 2 <html> 3 <head> 4 <meta charset=utf-8> 5 <title>CSS Transitions Test: transition of a custom property with "transition-behavior: allows-discrete"</title> 6 <meta name="assert" content="Checks that transitioning a custom property with 'transition-behavior: allows-discrete' works as expected"> 7 <link rel="help" href="https://drafts.csswg.org/css-transitions-2/#transition-behavior-property"> 8 <script src="/resources/testharness.js" type="text/javascript"></script> 9 <script src="/resources/testharnessreport.js" type="text/javascript"></script> 10 <script src="./support/helper.js" type="text/javascript"></script> 11 <style> 12 .target { 13 transition: --foo 10s step-start; 14 transition-behavior: allow-discrete; 15 --foo: bar; 16 } 17 </style> 18 </head> 19 <body> 20 <div id="log"></div> 21 <script> 22 promise_test(async t => { 23 const div = addDiv(t, { class: 'target' }); 24 25 let transitionCount = 0; 26 div.addEventListener("transitionstart", () => transitionCount++); 27 28 // Trigger a transition on the custom property. 29 getComputedStyle(div).getPropertyValue('--foo'); 30 div.style.setProperty('--foo', 'baz'); 31 getComputedStyle(div).getPropertyValue('--foo'); 32 33 // Wait two more frames to ensure only a single transition was started. 34 await waitForFrame(); 35 await waitForFrame(); 36 37 assert_equals(transitionCount, 1, 'A single "transitionstart" event was dispatched'); 38 }, 'It is possible to transition an unregistered custom property using "transition-behavior: allows-discrete"'); 39 40 promise_test(async t => { 41 const div = addDiv(t); 42 div.style.setProperty('--foo', 'bar'); 43 44 // Trigger a transition on the custom property. 45 getComputedStyle(div).getPropertyValue('--foo'); 46 div.style.transition = "--foo 10s allow-discrete"; 47 div.style.setProperty('--foo', 'baz'); 48 49 assert_equals(div.getAnimations()[0].transitionProperty, '--foo', 'A transition was started for the custom property'); 50 }, 'It is possible to transition an unregistered custom property using "transition-behavior: allows-discrete" when setting "transition-property" in the style change that yields the transition'); 51 52 </script> 53 </body> 54 </html>