Method once

front_end/core/common/Object.ts:138–140

(eventType: T)

    }

    once<T extends keyof Events>(eventType: T): Promise<Events[T]> {
      return this.__events.once(eventType);
    }

    removeEventListener<T extends keyof Events>(
        eventType: T, listener: (arg0: EventTargetEvent<Events[T]>) => void, thisObject?: Object): void {