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EventEmitter API Reference

The EventEmitter class provides a simple mechanism for implementing event-driven patterns in your application. It allows different parts of your code to subscribe to named events and to trigger those events with associated data.

EventEmitter Class​

Constructor​

constructor()

Creates a new EventEmitter instance.

Methods​

on(event: string, listener: (...args: any[]) => void): void​

Registers a listener function to be called when a specific event is emitted.

  • event: string: The name of the event to listen for.
  • listener: (...args: any[]) => void: The callback function to execute when the event is emitted. It will receive any arguments passed to the emit method.

emit(event: string, ...args: any[]): void​

Emits an event, causing all registered listeners for that event to be called with the provided arguments.

  • event: string: The name of the event to emit.
  • ...args: any[]: Optional arguments to pass to the listener functions.

off(event: string, listener: (...args: any[]) => void): void​

Removes a specific listener function for a given event.

  • event: string: The name of the event.
  • listener: (...args: any[]) => void: The listener function that was originally registered with on.

removeAllListeners(event?: string): void​

Removes all listeners for a specific event, or all listeners for all events if no event name is provided.

  • event?: string (optional): The name of the event for which to remove listeners. If omitted, all listeners for all events will be removed.

Example Usage​

import { EventEmitter } from "agent-forge"; // Assuming EventEmitter is exported from the main package

const myEmitter = new EventEmitter();

function handleTaskUpdate(taskId: string, status: string) {
  console.log(`Task ${taskId} updated to: ${status}`);
}

// Register a listener
myEmitter.on("taskUpdate", handleTaskUpdate);

// Emit an event
myEmitter.emit("taskUpdate", "123", "in-progress"); // Output: Task 123 updated to: in-progress

// Later, remove the listener
myEmitter.off("taskUpdate", handleTaskUpdate);

// This emission will no longer call handleTaskUpdate
myEmitter.emit("taskUpdate", "456", "completed");

// Remove all listeners for "taskUpdate" (if any remained)
myEmitter.removeAllListeners("taskUpdate");

// Remove all listeners from the emitter entirely
// myEmitter.removeAllListeners();

globalEventEmitter​

Agent Forge also exports a pre-instantiated globalEventEmitter:

export const globalEventEmitter = new EventEmitter();

This instance can be used for framework-level or application-wide events. However, for more localized event handling within your own modules or agent logic, it is often cleaner to create and use your own EventEmitter instances.