onlostpointercapture is an EventHandler property of the Element interface that returns the event handler (function) for the lostpointercapture event type.
The AbstractWorker.onerror property of the AbstractWorker interface represents an EventHandler, that is a function to be called when the error event occurs and bubbles through the Worker.
ongotpointercapture is an EventHandler property of the Element interface that returns the event handler (function) for the gotpointercapture event type.
The onmessage property of the Worker interface represents an EventHandler, that is a function to be called when the message event occurs. These events are of type MessageEvent and will be called when the worker's parent receives a message (i.e. from the DedicatedWorkerGlobalScope.postMessage method.
The onerror property of the WorkerGlobalScope interface represents an EventHandler to be called when the error event occurs and bubbles through the Worker.