The "p-map" NPM package is designed for mapping over promises concurrently. It is particularly useful when you have multiple promise-returning or async functions that need to run simultaneously with different inputs. This package offers a different approach compared to Promise.all(), as it allows you to not only control concurrency, but also decide whether or not to stop iteration when there's an error.

How do you use p-map?

To use the p-map package, you first need to install it using npm with the command npm install p-map. Once installed, you can import it into your JavaScript file. Here's an example of how to use it:

import pMap from 'p-map';
import got from 'got';

const sites = [
	getWebsiteFromUsername('sindresorhus'), //=> Promise
	'https://avajs.dev',
	'https://github.com'
];

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://avajs.dev/', 'https://github.com/']

In the above example, p-map is used to concurrently send GET requests to an array of websites and waits until they all respond before printing out a resulting array of the URLs.

Where are the p-map docs?

The documentation for "p-map" can be found within the README.md file of its GitHub repository, available at https://github.com/sindresorhus/p-map. The documentation includes an overview of the package's functions and how to use it, along with its API specifications, options, and examples of how to integrate it into your code.