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.