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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | 2x 8x 8x 8x 8x 8x 8x 8x 8x 67x 2x 65x 65x 65x 65x 16x 16x 6x 16x 49x 49x 49x 49x 2x 2x 49x 49x 49x 8x 18x 18x 2x 2x | /** * Execute an async function over an iterable collection * * @async * @function mapper * @param {*} iterable- An iterable collection * @param {function} mappingFunction - The async mapping function to execute * @param {number} [concurrency=Infinity] - The max number of concurrent calls * @returns {*} - The mapped results * @example * * const results = await mapper( * [1,2,3,4,5], * asyncFunction * ) */ const mapper = (iterable, mappingFunction, concurrency = Infinity) => new Promise((resolve, reject) => { const results = [] const iterator = iterable[Symbol.iterator]() let isRejected = false let isIterableComplete = false let resolvingCount = 0 let currentIndex = 0 const next = () => { if (isRejected) { return } const nextItem = iterator.next() const i = currentIndex currentIndex++ if (nextItem.done) { isIterableComplete = true if (resolvingCount === 0) { resolve(results) } return } resolvingCount++ return Promise.resolve(nextItem.value) .then(async element => { try { return await mappingFunction(element, i) } catch (err) { isRejected = true return reject(err) } }) .then(value => { results[i] = value resolvingCount-- return next() }) } for (let i = 0; i < concurrency; i++) { next() if (isIterableComplete) { break } } }) module.exports = mapper |