You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
79 lines
2.3 KiB
79 lines
2.3 KiB
# p-each-series [](https://travis-ci.com/github/sindresorhus/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
|
|
const pEachSeries = require('p-each-series');
|
|
|
|
const keywords = [
|
|
getTopKeyword(), //=> Promise
|
|
'rainbow',
|
|
'pony'
|
|
];
|
|
|
|
const iterator = async element => saveToDiskPromise(element);
|
|
|
|
(async () => {
|
|
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<Promise | unknown>`
|
|
|
|
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
|
|
const pEachSeries = require('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)
|