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https://github.com/sindresorhus/p-each-series
Iterate over promises serially
https://github.com/sindresorhus/p-each-series
Last synced: 2 months ago
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Iterate over promises serially
- Host: GitHub
- URL: https://github.com/sindresorhus/p-each-series
- Owner: sindresorhus
- License: mit
- Created: 2016-10-21T04:52:43.000Z (about 8 years ago)
- Default Branch: main
- Last Pushed: 2022-07-08T15:21:29.000Z (over 2 years ago)
- Last Synced: 2024-04-14T11:09:14.704Z (8 months ago)
- Language: JavaScript
- Size: 11.7 KB
- Stars: 49
- Watchers: 6
- Forks: 7
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- Funding: .github/funding.yml
- License: license
- Security: .github/security.md
Awesome Lists containing this project
- awesome-github-star - p-each-series
- promise-fun - p-each-series
README
# p-each-series
> Iterate over promises serially
Useful as a side-effect iterator. Prefer [`p-map`](https://github.com/sindresorhus/p-map) if you don't need side-effects, as it's concurrent.
## Install
```
$ npm install p-each-series
```
## Usage
```js
import pEachSeries from 'p-each-series';
const keywords = [
getTopKeyword(), //=> Promise
'rainbow',
'pony'
];
const iterator = async element => saveToDiskPromise(element);
console.log(await pEachSeries(keywords, iterator));
//=> ['unicorn', 'rainbow', 'pony']
```
## API
### pEachSeries(input, iterator)
Returns a `Promise` that is fulfilled when all promises in `input` and ones returned from `iterator` are fulfilled, or rejects if any of the promises reject. The fulfillment value is the original `input`.
#### input
Type: `Iterable`
Iterated over serially in the `iterator` function.
#### iterator(element, index)
Type: `Function`
Return value is ignored unless it's `Promise`, then it's awaited before continuing with the next iteration.
### pEachSeries.stop
Stop iterating through items by returning `pEachSeries.stop` from the iterator function.
```js
import pEachSeries from 'p-each-series';
// Logs `a` and `b`.
const result = await pEachSeries(['a', 'b', 'c'], value => {
console.log(value);
if (value === 'b') {
return pEachSeries.stop;
}
});
console.log(result);
//=> ['a', 'b', 'c']
```
## Related
- [p-map-series](https://github.com/sindresorhus/p-map-series) - Map over promises serially
- [p-series](https://github.com/sindresorhus/p-series) - Run promise-returning & async functions in series
- [p-pipe](https://github.com/sindresorhus/p-pipe) - Compose promise-returning & async functions into a reusable pipeline
- [p-waterfall](https://github.com/sindresorhus/p-waterfall) - Run promise-returning & async functions in series, each passing its result to the next
- [p-reduce](https://github.com/sindresorhus/p-reduce) - Reduce a list of values using promises into a promise for a value
- [p-map](https://github.com/sindresorhus/p-map) - Map over promises concurrently
- [More…](https://github.com/sindresorhus/promise-fun)