Baseline 2023
Newly available
Note: This feature is only available in Dedicated Web Workers.
The cancelAnimationFrame()
method of the DedicatedWorkerGlobalScope
interface cancels an animation frame request previously scheduled through a call to requestAnimationFrame()
.
Calling the cancelAnimationFrame()
method requires the current worker to have an associated owner window
. That means that the current worker must be created by window
or by a dedicated worker that also has an associated owner window
.
cancelAnimationFrame(handle)
Parameters
handle
The ID value returned by a call to requestAnimationFrame()
; the call must have been made in the same worker.
None (undefined
).
NotSupportedError
DOMException
Thrown if the method is not supported by the current worker.
On the main thread, we start by transferring the control of a <canvas>
element to an OffscreenCanvas
, using HTMLCanvasElement.transferControlToOffscreen()
and send to a message to "start"
its work to the worker, with the offscreen canvas:
const offscreenCanvas = document
.querySelector("canvas")
.transferControlToOffscreen();
worker.postMessage(
{
type: "start",
canvas: offscreenCanvas,
},
[offscreenCanvas],
);
When receiving the "start"
message, the worker starts the animation, moving the rectangle from left to right. Upon reception of a "stop"
message, it will stop the animation.
let ctx;
let pos = 0;
function draw(dt) {
ctx.clearRect(0, 0, 100, 100);
ctx.fillRect(pos, 0, 10, 10);
pos += 10 * dt;
self.requestAnimationFrame(draw);
}
self.addEventListener("message", (e) => {
if (e.data.type === "start") {
const transferredCanvas = e.data.canvas;
ctx = transferredCanvas.getContext("2d");
self.requestAnimationFrame(draw);
}
if (e.data.type === "stop") {
self.cancelAnimationFrame(handle);
}
});
Finally, if needed, the main thread can send a "stop"
message to the worker to stop the animation:
worker.postMessage({
type: "stop",
});
Specifications Browser compatibility See also
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4