Introduction to component-emitter

Welcome to an in-depth guide about component-emitter, a popular JavaScript library that enables the implementation of the event-driven programming model. This lightweight library is perfect for developing Node.js and JavaScript applications with efficient event management.

Core APIs and Their Usage

Basic Usage

  const Emitter = require('component-emitter');
  const emitter = new Emitter();

emitter.on(event, listener)

Registers a listener for the given event.

  emitter.on('event', () => {
    console.log('Event occurred!');
  });

emitter.emit(event, […args])

Triggers an event, optionally with arguments.

  emitter.emit('event'); // console logs: 'Event occurred!'

emitter.off(event, listener)

Removes the specified listener for the given event.

  function handler() {
    console.log('Event happened');
  }
  emitter.on('event', handler);
  emitter.off('event', handler);

emitter.once(event, listener)

Registers a listener to be called only the first time the event is fired.

  emitter.once('event', () => {
    console.log('This will only log once.');
  });
  emitter.emit('event'); // logs: 'This will only log once.'
  emitter.emit('event'); // no log

App Example

Below is an example that demonstrates the component-emitter’s API usage in a Node.js app for better understanding:

  const Emitter = require('component-emitter');
  
  // Initializing the emitter
  const emitter = new Emitter();
  
  // Defining the listeners
  emitter.on('dataReceived', (data) => {
    console.log('Data received:', data);
  });
  
  emitter.once('onlyOnce', () => {
    console.log('This event listener will run only once.');
  });
  
  function logEvent() {
    console.log('Event logged.');
  }
  
  emitter.on('log', logEvent);
  emitter.emit('dataReceived', { id: 1, name: 'Sample Data' });
  emitter.emit('onlyOnce');
  emitter.emit('onlyOnce');
  emitter.emit('log');
  
  // Removing the 'log' event listener
  emitter.off('log', logEvent);
  emitter.emit('log'); // No output as the listener has been removed

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