expo-modules-core/build/ts-declarations/EventEmitter.d.ts

The core of Expo Modules architecture

/**
 * Base type of the events map, whose keys represent supported event names
 * and values are the signatures of the listener for that specific event.
 */
export type EventsMap = Record<string, (...args: any[]) => void>;
/**
 * A subscription object that allows to conveniently remove an event listener from the emitter.
 */
export type EventSubscription = {
    /**
     * Removes an event listener for which the subscription has been created.
     * After calling this function, the listener will no longer receive any events from the emitter.
     */
    remove(): void;
};
/**
 * A class that provides a consistent API for emitting and listening to events.
 * It shares many concepts with other emitter APIs, such as Node's EventEmitter and `fbemitter`.
 * When the event is emitted, all of the functions attached to that specific event are called *synchronously*.
 * Any values returned by the called listeners are *ignored* and discarded.
 * Its implementation is written in C++ and common for all the platforms.
 */
export declare class EventEmitter<TEventsMap extends EventsMap = Record<never, never>> {
    /**
     * A dummy private property with the given generic type. It is required for TypeScript to correctly infer this subtype.
     * E.g. `useEvent` would not be able to infer the events map which results in accepting any string as the event name.
     * @private
     * @deprecated
     */
    _TEventsMap_DONT_USE_IT?: TEventsMap;
    /**
     * Creates a new event emitter instance.
     */
    constructor();
    /**
     * @deprecated As of Expo SDK 52 the given object is already an EventEmitter.
     * Creating a new one is not necessary.
     * @hidden
     */
    constructor(object: EventEmitter);
    /**
     * Adds a listener for the given event name.
     */
    addListener<EventName extends keyof TEventsMap>(eventName: EventName, listener: TEventsMap[EventName]): EventSubscription;
    /**
     * Removes a listener for the given event name.
     */
    removeListener<EventName extends keyof TEventsMap>(eventName: EventName, listener: TEventsMap[EventName]): void;
    /**
     * Removes all listeners for the given event name.
     */
    removeAllListeners(eventName: keyof TEventsMap): void;
    /**
     * Synchronously calls all the listeners attached to that specific event.
     * The event can include any number of arguments that will be passed to the listeners.
     */
    emit<EventName extends keyof TEventsMap>(eventName: EventName, ...args: Parameters<TEventsMap[EventName]>): void;
    /**
     * Returns a number of listeners added to the given event.
     */
    listenerCount<EventName extends keyof TEventsMap>(eventName: EventName): number;
    /**
     * Function that is automatically invoked when the first listener for an event with the given name is added.
     * Override it in a subclass to perform some additional setup once the event started being observed.
     */
    startObserving?<EventName extends keyof TEventsMap>(eventName: EventName): void;
    /**
     * Function that is automatically invoked when the last listener for an event with the given name is removed.
     * Override it in a subclass to perform some additional cleanup once the event is no longer observed.
     */
    stopObserving?<EventName extends keyof TEventsMap>(eventName: EventName): void;
}
//# sourceMappingURL=EventEmitter.d.ts.map