var emitter= new EventEmitter2();

EventEmitter2.once(emitter, 'event', {
    timeout: 0,
    Promise: Promise, // a custom Promise constructor
    overload: false // overload promise cancellation api if exists with library implementation
}).then(function(data){
    console.log(data); // [1, 2, 3]
});

emitter.emit('event', 1, 2, 3);

import { Component, EventEmitter, Input, Output } from '@angular/core';

@Component({
  selector: 'app-voter',
  template: `
    <h4>{{name}}</h4>
    <button type="button" (click)="vote(true)"  [disabled]="didVote">Agree</button>
    <button type="button" (click)="vote(false)" [disabled]="didVote">Disagree</button>
  `
})
export class VoterComponent {
  @Input()  name = '';
  @Output() voted = new EventEmitter<boolean>();
  didVote = false;

  vote(agreed: boolean) {
    this.voted.emit(agreed);
    this.didVote = true;
  }
}

var emitter= new EventEmitter2({
    wildcard: true
});
emitter.on('a.b.c', function(){});
emitter.on(['z', 'x', 'c'], function(){});
console.log(emitter.eventNames()) // [ 'z.x.c', 'a.b.c' ]

var EventEmitter2= require('eventemitter2');
var emitter= new EventEmitter2();

emitter.on('event', function(){
    console.log('The event was raised!');
}, {async: true});

emitter.emit('event');
console.log('emitted');

var emitter= new EventEmitter2({
    wildcard: true
});
emitter.on('a.b.c', function(){});
emitter.on(['z', 'x', Symbol()], function(){});
console.log(emitter.eventNames()) // [ [ 'z', 'x', Symbol() ], 'a.b.c' ]