event-to-promise

Create a promise waiting for an event

Install

Download manually or with package-manager.

npm

npm install --save event-to-promise

Example

var eventToPromise = require('event-to-promise')

function createServer (port) {
  var server = require('http').createServer()
  server.listen(port)

  // The server will be returned once it has started listening.
  //
  // If an error happened, it will be forwarded instead.
  return eventToPromise(server, 'listening').then(function () {
    return server
  })
}

// Using plain promise.
createServer(80).then(function (server) {
  console.log('Server listening on http://localhost:80/')
}).catch(function (error) {
  console.error('Server could not start:', error)
})

Event better using ES2016 asynchronous functions:

import eventToPromise from 'event-to-promise'

async function createServer (port) {
  var server = require('http').createServer()
  server.listen(port)

  await eventToPromise(server, 'listening')

  return server
}

async function main () {
  try {
    const server = await createServer(80);
    console.log('Server listening on http://localhost:80/');
  } catch (error) {
    console.error('Server could not start:', error);
  }
}

main()

API

eventToPromise(emitter, event, [options])

Wait for one event. The first parameter of the emitted event is used to resolve/reject the promise.

emitter

Required Type: Object

The event emitter you want to watch an event on.

event

Required Type: string

The name of the event you want to watch.

options

array

Type: boolean Default: false

If true, all parameters of the emitted events are put in an array which is used to resolve/reject the promise.

error

Type: string Default: "error"

The name of the event which rejects the promise.

ignoreErrors

Type: boolean Default: false

Whether the error event should be ignored and not reject the promise.

eventToPromise.multi(emitter, successEvents, errorEvents)

Wait for one of multiple events. The array of all the parameters of the emitted event is used to resolve/reject the promise.

The array also has an event property indicating which event has been emitted.

emitter

Required Type: Object

The event emitter you want to watch an event on.

successEvents

Required Type: Array<string>

The names of the events which resolve the promise.

errorEvents

Type: Array<string> Default: [ 'error' ]

The names of the events which reject the promise.

Contributing

Contributions are very welcome, either on the documentation or on the code.

You may:

• report any issue you've encountered;
• fork and create a pull request.

License

ISC © Julien Fontanet