https://github.com/martinheidegger/run-each
A very small, flexible, parallel async iteration helper that has first-class support for Iterators and concurrency.
https://github.com/martinheidegger/run-each
async callback concurrency each iterable iterator javascript parallel
Last synced: 4 months ago
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A very small, flexible, parallel async iteration helper that has first-class support for Iterators and concurrency.
- Host: GitHub
- URL: https://github.com/martinheidegger/run-each
- Owner: martinheidegger
- License: mit
- Created: 2019-01-04T17:50:13.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2019-01-04T18:06:47.000Z (over 6 years ago)
- Last Synced: 2025-03-11T02:39:03.806Z (4 months ago)
- Topics: async, callback, concurrency, each, iterable, iterator, javascript, parallel
- Language: JavaScript
- Size: 6.84 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: Readme.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
README
# run-each
[](https://standardjs.com)
[](https://codeclimate.com/github/martinheidegger/run-each/maintainability)
[](https://codeclimate.com/github/martinheidegger/run-each/test_coverage)
`run-each` is a **very small**, **flexible**, **parallel** async iteration helper that has first-class support for [Iterators][]
(unlike other libraries, which mostly break with iterators) and **concurrency**. It also has complete TypeScript header files for
comfortable integration.
[Iterators]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
`npm i run-each --save`
It is similar to [`each`][], [`async-each`][], [`each-async`][], ... and many other.
```javascript
const { runEach } = require('run-each')
runEach(
[
function (callback) {
callback()
},
function (callback) {
callback()
}
],
function (err) {
// Done once all functions are done
}
)
```
[`each`]: https://www.npmjs.com/package/each
[`async-each`]: https://www.npmjs.com/package/each
[`each-async`]: https://www.npmjs.com/package/each-async
There are several things that make this different:
- It returns an `Iterable` object instead of an Array.
- It supports `Promises` in case you prefer to use async/await with your API's
- It supports `concurrency` limits to limit the amount of commands executed at the same time.
## Iterable results
Like in other libraries you can get the result, but unlike other libraries, its not
an Array, so you need to apply an `Array.from` to it.
```javascript
runEach([
function (callback) {
callback('a')
},
function (callback) {
callback('b')
}
], function (err, data) {
Array.from(data) === ['a', 'b'] // the order is protected
})
```
_Note:_ This is more of an internal detail, but if the passed-in function doesn't have
a second parameter, the data will not be collected.
```javascript
runEach([], function () {
console.log(arguments.length) // 1
})
runEach([], function (err, data) {
console.log(arguments.length) // 2
})
```
## Promise support
If you don't pass in a callback handler at the end, it will automatically return a Promise.
```javascript
runEach([/*...*/]).then(function () {
// all done
})
```
## Concurrency
By passing a concurrency limit to the runner, it will limit the amount of parallel
executions
```javascript
runEach([/*...*/], 1).then(function () {
// now each operation is run in series.
})
runEach([/*...*/], 2).then(function () {
// now two operations are run at the same time
})
```
### License
MIT