events-promisify

Just another JavaScript EventEmitter for Promise.

Installation

Node.js

$ npm install --save events-promisify

Browser via CDN

<script src="https://cdn.jsdelivr.net/npm/events-promisify/dist/index.umd.js"></script>

Usage

import EventEmitter from 'events-promisify'

const ee = new EventEmitter()

ee.on('event-a', function () {
  /**
   * listener can return a Promise instance
   * all listeners will be executed serially
   */
  return new Promise(function (resolve, reject) {
    /** resolve asynchronously */
    setTimeout(function () {
      resolve('the result')
    }, 1e3)
    /**
     * ...or reject with an Error instance
     * will cause the emitter rejected immediately
     */
    // reject(new Error('Failed!'))
  })
})

ee.once(['event-a', 'event-b'], function (arg1, arg2) {
  /** ...or return anything */
  return `foo ${arg1} bar ${arg2}`
})

ee.on('event-b', function () {
  /**
   * ...or throw an Error instance
   * also will cause the emitter rejected immediately
   */
  throw new Error('Failed!')
})

ee.emit('event-a', 11, 22)
  .then(function (results) {
    /** event finished */
  })
  .catch(function (error) {
    /** event failed with error */
  })

API

ee.on(<eventName>, <func>)

Listen on events.

| Parameter | Type | Description | Default | | --- | --- | --- | --- | | eventName | String|String[] | The event name or array of event names. | (required) | | func | Function | The listener function. | (required) |

• Returns: void

ee.once(<eventName>, <func>)

Listen on events for one-time execution.

| Parameter | Type | Description | Default | | --- | --- | --- | --- | | eventName | String|String[] | The event name or array of event names. | (required) | | func | Function | The listener function. | (required) |

• Returns: void

ee.off(<eventName>, <func>)

Remove listener for events.

| Parameter | Type | Description | Default | | --- | --- | --- | --- | | eventName | String|String[] | The event name or array of event names. | (required) | | func | Function | The listener function. | (required) |

• Returns: void

ee.emit(<eventName>, [...args])

Listen on events.

| Parameter | Type | Description | Default | | --- | --- | --- | --- | | eventName | String | The event name. | (required) | | args | ...any | Arguments passed to listeners. | |

• Returns: Promise<any>

License

MIT