| <!DOCTYPE html> |
| <body> |
| <style> |
| body, #cover { |
| background-color: green; |
| } |
| |
| #target, #cover { |
| position: absolute; |
| top: 0; |
| left: 0; |
| height: 100px; |
| } |
| |
| #target { |
| width: 100px; |
| background-color: red; |
| } |
| |
| /* This element covers the first half of the area traveled by the animated target. If the animation did not |
| respect the playbackRate, then red would appear since the animated target would travel to the right of |
| the cover element. */ |
| #cover { |
| left: 100px; |
| width: 200px; |
| } |
| |
| </style> |
| <div id="target"></div> |
| <div id="cover"></div> |
| <script> |
| |
| (async () => { |
| if (window.testRunner) |
| testRunner.waitUntilDone(); |
| |
| // Start an animation. |
| const animation = document.getElementById("target").animate({ transform: ["translateX(100px)", "translateX(300px)"] }, { duration: 1000, fill: "both" }); |
| |
| // Seek it to its halfway point, the target should align with the right edge of the cover. |
| animation.currentTime = animation.effect.getTiming().duration / 2; |
| |
| // Make it play backwards. |
| animation.playbackRate = -1; |
| |
| // Wait a few frames. |
| await animation.ready; |
| await new Promise(requestAnimationFrame); |
| await new Promise(requestAnimationFrame); |
| await new Promise(requestAnimationFrame); |
| |
| // At this point, if the target were ignoring the playbackRate, it would peek a little to the right of the cover. |
| if (window.testRunner) |
| testRunner.notifyDone(); |
| })(); |
| |
| </script> |
| </body> |
