EventEmitter Implementation

This repository contains an implementation of a TypeScript-based event emitter utility, including a pair of interfaces (createEmitterListener and EventEmitter) for managing events and their listeners. This utility is designed to provide a lightweight and type-safe mechanism for emitting and handling events in TypeScript projects.

Features

• Type-Safe Event Handling: Both createEmitterListener and EventEmitter allow for type-safe event handling, ensuring that event listeners receive the correct parameters.
• Event Subscription and Unsubscription: Easily subscribe to and unsubscribe from events using the on and off methods.
• Independent Instances: Multiple instances can operate independently without interference, preventing event crossover.
• Automatic Unsubscription: The on method returns a function that can be called to automatically unsubscribe the event listener.

Installation

To use this utility in your project, simply clone the repository and install the dependencies:

git clone https://github.com/yourusername/event-emitter-ts.git
cd event-emitter-ts
npm install

Usage

createEmitterListener

The createEmitterListener function provides an object with listener and emit methods. Here's an example:

const { listener, emit } = createEmitterListener<{
  win: [];
  speak: [message: string];
}>();

listener.on('win', () => {
  console.log('You win!');
});

listener.on('speak', (message) => {
  console.log(message);
});

emit('win'); // Logs: "You win!"
emit('speak', 'Hello, world!'); // Logs: "Hello, world!"

EventEmitter

The EventEmitter class merges the on, off, and emit methods together in a single instance:

const eventEmitter = new EventEmitter<{
  win: [];
  speak: [message: string];
}>();

eventEmitter.on('win', () => {
  console.log('You win!');
});

eventEmitter.on('speak', (message) => {
  console.log(message);
});

eventEmitter.emit('win'); // Logs: "You win!"
eventEmitter.emit('speak', 'Hello, world!'); // Logs: "Hello, world!"

Running Tests

This repository includes a comprehensive test suite to ensure the functionality of the createEmitterListener and EventEmitter implementations.

To run the tests, use the following command:

npm test

The test suite uses Mocha, Chai, and Sinon to cover various scenarios, including multiple instances and automatic unsubscription.

License

This project is licensed under the ISC License. See the LICENSE file for details.