Class InMemoryEventBus

In-memory event bus implementation.

Provides a simple, synchronous event bus with pub/sub capabilities. Each event type can have multiple subscribers.

Example

const eventBus = new InMemoryEventBus();

// Subscribe to event
eventBus.subscribe(UserCreatedEvent, async (event) => {
  await sendWelcomeEmail(event.userId);
});

eventBus.subscribe(UserCreatedEvent, async (event) => {
  await logUserCreation(event.userId);
});

// Publish event
await eventBus.publish(new UserCreatedEvent('123', 'john@example.com'));

Implements

  • EventBus

Constructors

constructor

Methods

subscribe publish publishAll unsubscribe getSubscriberCount clearSubscribers clear

Constructors

constructor

Methods

subscribe

  • subscribe<TEvent extends Event>(
        eventType: new (...args: never[]) => TEvent,
        handler: EventHandler<TEvent> | (event: TEvent) => Promise<void>,
    ): void

    Subscribes to an event type.

    Multiple handlers can subscribe to the same event type.

    Type Parameters

    • TEvent extends Event

      The event type

    Parameters

    • eventType: new (...args: never[]) => TEvent

      The event class constructor

    • handler: EventHandler<TEvent> | (event: TEvent) => Promise<void>

      The handler function

    Returns void

    Example

    eventBus.subscribe(UserCreatedEvent, async (event) => {
      console.log('User created:', event.userId);
    });

publish

  • publish(event: Event): Promise<void>

    Publishes an event to all subscribers.

    All handlers are invoked in parallel.

    Parameters

    • event: Event

      The event to publish

    Returns Promise<void>

    Example

    await eventBus.publish(new UserCreatedEvent('123', 'john@example.com'));

publishAll

  • publishAll(events: Event[]): Promise<void>

    Publishes multiple events to their subscribers.

    Events are published in order, but handlers for each event run in parallel.

    Parameters

    • events: Event[]

      The events to publish

    Returns Promise<void>

    Example

    await eventBus.publishAll([
      new UserCreatedEvent('123', 'john@example.com'),
      new WelcomeEmailSentEvent('123')
    ]);

unsubscribe

  • unsubscribe<TEvent extends Event>(
        eventType: new (...args: never[]) => TEvent,
        handler: EventHandler<TEvent> | (event: TEvent) => Promise<void>,
    ): void

    Unsubscribes a handler from an event type.

    Type Parameters

    • TEvent extends Event

      The event type

    Parameters

    • eventType: new (...args: never[]) => TEvent

      The event class constructor

    • handler: EventHandler<TEvent> | (event: TEvent) => Promise<void>

      The handler function to remove

    Returns void

    Example

    const handler = async (event) => console.log(event);
    eventBus.subscribe(UserCreatedEvent, handler);
    eventBus.unsubscribe(UserCreatedEvent, handler);

getSubscriberCount

  • getSubscriberCount(eventType: new (...args: never[]) => Event): number

    Gets the number of subscribers for an event type.

    Parameters

    • eventType: new (...args: never[]) => Event

      The event class constructor

    Returns number

    The number of subscribers

clearSubscribers

  • clearSubscribers(eventType: new (...args: never[]) => Event): void

    Clears all subscribers for a specific event type.

    Parameters

    • eventType: new (...args: never[]) => Event

      The event class constructor

    Returns void

clear

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