Event Emitter

Type-safe Event Emitter implementation that works in browsers. For server usage, stick with the nodejs EventEmitter.

Why should I use Event Emitter instead of EventTarget?

Don't. If EventTarget meets your needs, then use it - you will save on package size and use a standard way to handle events. But if you have taken a look at the compatibility table, you will find one alarming thing. The EventTarget's constructor has been supported in the major browsers only since late 2020, so trying to run class MyClass extends EventTarget {} in older browser will crash. Also if you would like your events to be type-safe, then EventTarget won't help you there.

Installation

npm install @alesmenzel/event-emitter

Usage

type MyEvents = {
  count: (count: number) => void
  // define all your events and their data
}

// Create the EventEmitter
const emitter = new EventEmitter<MyEvents>()

// Listen on events
// Option 1
const unsubscribe = emitter.on('count', (count) => {
  console.log('count:', count)
})
// Option 2
const handler = (count) => {
  console.log('count:', count)
}
emitter.on('count', handler)

// Emit events
emitter.emit('count', 1)
emitter.emit('count', 2)
emitter.emit('count', 3)

// Stop listening to events
// Option 1
unsubscribe()
// Option 2
emitter.off('count', handler)

// Stop listening on events of a certain type
emitter.off('count')

// Stop listening on all events
emitter.off()