https://github.com/loilo/node-event-emitting-promise
An extended Promise object implementing Node's EventEmitter methods
https://github.com/loilo/node-event-emitting-promise
Last synced: 4 months ago
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An extended Promise object implementing Node's EventEmitter methods
- Host: GitHub
- URL: https://github.com/loilo/node-event-emitting-promise
- Owner: loilo
- License: mit
- Created: 2017-05-03T10:52:37.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2017-05-04T07:07:51.000Z (about 9 years ago)
- Last Synced: 2025-02-15T19:02:03.944Z (over 1 year ago)
- Language: JavaScript
- Size: 11.7 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# event-emitting-promise
An extended [Promise](https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Promise) object implementing Node's [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter) methods
## Reasoning
From time to time, I found myself in the need to combine the comfortable program flow that Promises offer (especially with `async`/`await`) with the verbose usefulness of events.
My usual use case is the creation of CLI versions from functions I've wrote. Using this package, that can be done pretty easily.
## Install
```bash
# With yarn
yarn add event-emitting-promise
# With npm
npm install --save event-emitting-promise
```
## Usage
Let's say we want to create a programmatic and a CLI version of a function called `myFunc()`.
Consider this the `my-func.js`:
```javascript
const EventEmittingPromise = require('event-emitting-promise')
// Asynchronous partial tasks
const { task1, task2, task3 } = require('./somewhere')
module.exports = function myFunc () {
// The EventEmittingPromise constructor callback takes an
// additional argument called "emit", which is the
// EventEmitter.prototype.emit method.
return new EventEmittingPromise(async (resolve, reject, emit) => {
try {
const result1 = await task1()
emit('partial', 'task1', result1)
const result2 = await task2()
emit('partial', 'task2', result2)
const result3 = await task3()
emit('partial', 'task3', result3)
resolve({
task1: result1,
task2: result2,
task3: result3
})
} catch (err) {
reject(err)
}
})
}
```
And this the `my-func-cli.js`:
```javascript
const myFunc = require('./my-func')
module.exports = function myFuncCLI () {
return myFunc()
// The created Promise provides all of the EventEmitter methods
// (except emit) and allows chaining them.
.on('partial', (name, result) => {
console.log(
`Partial task ${name} has finished with result:`,
result
)
})
.then(() => {
console.log('Done.')
})
.catch(err => {
console.error('An error occurred:', err)
})
}
```
That way, places calling `myFunc()` can easily be informed about the progress of the function call.