86 lines
2.2 KiB
Markdown
86 lines
2.2 KiB
Markdown
# p-map [](https://travis-ci.org/sindresorhus/p-map)
|
|
|
|
> Map over promises concurrently
|
|
|
|
Useful when you need to run promise-returning & async functions multiple times with different inputs concurrently.
|
|
|
|
|
|
## Install
|
|
|
|
```
|
|
$ npm install p-map
|
|
```
|
|
|
|
|
|
## Usage
|
|
|
|
```js
|
|
const pMap = require('p-map');
|
|
const got = require('got');
|
|
|
|
const sites = [
|
|
getWebsiteFromUsername('sindresorhus'), //=> Promise
|
|
'ava.li',
|
|
'todomvc.com',
|
|
'github.com'
|
|
];
|
|
|
|
(async () => {
|
|
const mapper = async site => {
|
|
const {requestUrl} = await got.head(site);
|
|
return requestUrl;
|
|
};
|
|
|
|
const result = await pMap(sites, mapper, {concurrency: 2});
|
|
|
|
console.log(result);
|
|
//=> ['http://sindresorhus.com/', 'http://ava.li/', 'http://todomvc.com/', 'http://github.com/']
|
|
})();
|
|
```
|
|
|
|
## API
|
|
|
|
### pMap(input, mapper, [options])
|
|
|
|
Returns a `Promise` that is fulfilled when all promises in `input` and ones returned from `mapper` are fulfilled, or rejects if any of the promises reject. The fulfilled value is an `Array` of the fulfilled values returned from `mapper` in `input` order.
|
|
|
|
#### input
|
|
|
|
Type: `Iterable<Promise|any>`
|
|
|
|
Iterated over concurrently in the `mapper` function.
|
|
|
|
#### mapper(element, index)
|
|
|
|
Type: `Function`
|
|
|
|
Expected to return a `Promise` or value.
|
|
|
|
#### options
|
|
|
|
Type: `Object`
|
|
|
|
##### concurrency
|
|
|
|
Type: `number`<br>
|
|
Default: `Infinity`<br>
|
|
Minimum: `1`
|
|
|
|
Number of concurrently pending promises returned by `mapper`.
|
|
|
|
|
|
## Related
|
|
|
|
- [p-all](https://github.com/sindresorhus/p-all) - Run promise-returning & async functions concurrently with optional limited concurrency
|
|
- [p-filter](https://github.com/sindresorhus/p-filter) - Filter promises concurrently
|
|
- [p-times](https://github.com/sindresorhus/p-times) - Run promise-returning & async functions a specific number of times concurrently
|
|
- [p-props](https://github.com/sindresorhus/p-props) - Like `Promise.all()` but for `Map` and `Object`
|
|
- [p-map-series](https://github.com/sindresorhus/p-map-series) - Map over promises serially
|
|
- [p-queue](https://github.com/sindresorhus/p-queue) - Promise queue with concurrency control
|
|
- [More…](https://github.com/sindresorhus/promise-fun)
|
|
|
|
|
|
## License
|
|
|
|
MIT © [Sindre Sorhus](https://sindresorhus.com)
|