CanvasRenderingContext2D: isContextLost() method

The CanvasRenderingContext2D.isContextLost() method of the Canvas 2D API returns true if the rendering context is lost (and has not yet been reset). This might occur due to driver crashes, running out of memory, and so on.

If the user agent detects that the canvas backing storage is lost it will fire the contextlost event at the associated HTMLCanvasElement. If this event is not cancelled it will attempt to reset the backing storage to the default state (this is equivalent to calling CanvasRenderingContext2D.reset()). On success it will fire the contextrestored event, indicating that the context is ready to reinitialize and redraw.

Syntax

isContextLost()

Parameters

None.

Return value

true if the rendering context was lost; false otherwise.

Examples

const ctx = canvas.getContext("2d");

if (ctx.isContextLost()) {
  console.log("Context is lost");
}

Specifications

Browser compatibility

See also

• The interface defining this method: CanvasRenderingContext2D
• HTMLCanvasElement: contextlost event
• HTMLCanvasElement: contextrestored event