JarCastingp-map 
Map over promises concurrently
Useful when you need to run promise-returning & async functions multiple times with different inputs concurrently.
This is different from Promise.all() in that you can control the concurrency and also decide whether or not to stop iterating when there's an error.
Install
$ npm install p-map
Usage
const pMap = require('p-map');
const got = require('got');
const sites = [
getWebsiteFromUsername('https://sindresorhus'), //=> Promise
'https://ava.li',
'https://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);
//=> ['https://sindresorhus.com/', 'https://ava.li/', 'https://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 | unknown>
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 (Integer)
Default: Infinity
Minimum: 1
Number of concurrently pending promises returned by mapper.
stopOnError
Type: boolean
Default: true
When set to false, instead of stopping when a promise rejects, it will wait for all the promises to settle and then reject with an aggregated error containing all the errors from the rejected promises.
p-map for enterprise
Available as part of the Tidelift Subscription.
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Related
- p-all - Run promise-returning & async functions concurrently with optional limited concurrency
- p-filter - Filter promises concurrently
- p-times - Run promise-returning & async functions a specific number of times concurrently
- p-props - Like
Promise.all()but forMapandObject - p-map-series - Map over promises serially
- p-queue - Promise queue with concurrency control
- More…