umitt

About

An upgraded version of Events in Node.js core API for the browser. We only get features that we think you really need, not the whole.

Usage

Installation

$ npm install umitt

// or yarn
$ yarn add umitt

CDN

// unpkg
<script src="https://unpkg.com/umitt/dist/umitt.js"></script>

// jsdelivr
<script src="https://cdn.jsdelivr.net/npm/umitt/dist/umitt.js"></script>

Note use CDN in browser, you can call umitt from Window API. it is available at window.umitt

Example

import Events from 'umitt'

const emitter = new Events()

// add event listener
emitter.on('connection', (name) => {
  console.log(name, 'connected!');
})

// emit event
emitter.emit('connection', 'Hieu Lam')

Documents

Events: emitter

The Events class is defined and exposed by the events module:

import Events from 'umitt'

const emitter = new Events()

All EventEmitters emit the event 'newListener' when new listeners are added and 'removeListener' when existing listeners are removed.

addListener(eventName, listener)

Alias for on(eventName, listener).

emitter.addListener('eventName', callback)

emit(eventName[, ...args])

Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.

// without argument
emitter.emit('eventName')

// with argument
emitter.emit('eventName', 'arg1', 'arg2', ...)

eventNames()

Returns an array listing the events for which the emitter has registered listeners.

emitter.eventsName()

Example

const callback = () => {}

emitter.on('eventName', callback)

console.log(emitter.eventNames())

// prints: [ 'eventName' ]

listeners(eventName)

Returns a copy of the array of listeners for the event named eventName.

emitter.listeners('eventName')

Example

const callback = () => {}

emitter.on('eventName', callback)

console.log(emitter.listeners('eventName'))

// prints: [ [Function] ]

off(eventName, listener)

Alias for removeListener(eventName, listener).

on(eventName, listener)

Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

// without argument
emitter.on('eventName', () => {
  console.log('called!');
});

// with argument
emitter.on('eventName', (arg1, arg2) => {
  console.log('called!', [arg1, arg2]);
});

Example

emitter.on('sayName', (name) => {
  console.log('my name is', name)
})
emitter.emit('sayName', 'Hieu Lam')

// prints:
// my name is Hieu Lam

once(eventName, listener)

Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.

// without argument
emitter.once('eventName', () => {
  console.log('called!');
});

// with argument
emitter.once('eventName', (arg1, arg2) => {
  console.log('called!', [arg1, arg2]);
});

Example

emitter.once('sayName', (name) => {
  console.log('my name is', name)
})
emitter.emit('sayName', 'Hieu Lam')
emitter.emit('sayName', 'John Smith')

// prints:
// my name is Hieu Lam

removeAllListeners([eventName])

Removes all listeners, or those of the specified eventName.

emitter.removeAllListeners(['eventName'])

removeListener(eventName, listener)

Removes the specified listener from the listener array for the event named eventName. removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

emitter.removeListener('eventName', callback)

Example

const callback = (name) => {
  console.log('my name is', name)
}
emitter.on('sayName', callback)
emitter.emit('sayName', 'Hieu Lam')
// prints: my name is Hieu Lam

emitter.removeListener('sayName', callback)
emitter.emit('sayName', 'Hieu Lam')
// nothing

disable(eventName)

Disable the specified listeners for the event named eventName. When listeners was disabled, it's still existed but not run when emit called. To enbale listeners for the event, just use enable(eventName).

emitter.disable('eventName')

Example

const callback = (name) => {
  console.log('my name is', name)
}
emitter.on('sayName', callback)
emitter.emit('sayName', 'Hieu Lam')
// prints: my name is Hieu Lam

emitter.disable('sayName')
emitter.emit('sayName', 'Hieu Lam')
// nothing

emitter.enable('sayName')
emitter.emit('sayName', 'Hieu Lam')
// prints: my name is Hieu Lam

enable(eventName)

Enable the specified listeners for the event named eventName.

emitter.enable('eventName')

Example

const callback = (name) => {
  console.log('my name is', name)
}
emitter.on('sayName', callback)
emitter.emit('sayName', 'Hieu Lam')
// prints: my name is Hieu Lam

emitter.disable('sayName')
emitter.emit('sayName', 'Hieu Lam')
// nothing

emitter.enable('sayName')
emitter.emit('sayName', 'Hieu Lam')
// prints: my name is Hieu Lam