Mapping across an async array response

async_options.js

'use strict'
const async = require('async')

const a = [0,1,2,3,4,5,6,7,8,9]

/*
async.mapLimit(a, 2, fancy, (err, result) => {
	console.log(`err: ${err}, result: ${result}`)
})
*/

function fancy(value, cb) {
	return setTimeout(() => {
		console.log(value)
		cb(null, value)
	}, 500)
}

function fancyPromise(value) {
	return new Promise((resolve, reject) => {
		return setTimeout(() => {
			return resolve(value * 2)
		}, 500)
	})
}

Promise.all(a.map(fancyPromise))
.then(results => {
	console.log(results)
})
.catch(err => {
	console.error(err)
})