files/en-us/web/api/offscreencanvas/contextrestored_event/index.md
{{APIRef("Canvas API")}}
The contextrestored event of the {{domxref("OffscreenCanvas")}} interface is fired if the browser restores an OffscreenCanvasRenderingContext2D context that was previously lost.
You can redraw, re-retrieve resources, and reinitialize the state of your context after receiving this event.
Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}}, or set an event handler property.
addEventListener("contextrestored", (event) => { })
oncontextrestored = (event) => { }
A generic {{domxref("Event")}}.
The code fragment below detects the context restored event.
const canvas = new OffscreenCanvas(256, 256);
const gl = offscreen.getContext("2d");
canvas.addEventListener("contextrestored", (e) => {
console.log(e);
// call to redrawCanvas() or similar
});
{{Specifications}}
{{Compat}}