p-reduce
Advanced tools
Package description
The p-reduce npm package is a utility that allows you to reduce a list of values using promises in series. It is particularly useful when you need to perform a series of asynchronous operations in sequence and combine their results into a single value.
Promise Reduction
This feature allows you to reduce an array of promises to a single promise that resolves to a value. The code sample demonstrates how to sum a series of numbers wrapped in promises.
const pReduce = require('p-reduce');
const promiseArray = [Promise.resolve(1), Promise.resolve(2), Promise.resolve(3)];
pReduce(promiseArray, (total, value) => Promise.resolve(total + value), 0).then(result => console.log(result)); // 6Bluebird is a comprehensive promise library that includes a 'reduce' method similar to p-reduce. It offers additional features like cancellation, progress updates, and more efficient performance in some cases.
Async is a utility module which provides straight-forward, powerful functions for working with asynchronous JavaScript. It includes 'reduce' and 'reduceRight' functions that work with async operations, but it's not promise-based by default.
Q is a promise library that includes a 'reduce' method for promises. It is similar to p-reduce but also includes other features like making functions return promises and utilities for handling groups of promises.
Readme
Reduce a list of values using promises into a promise for a value
Useful when you need to calculate some accumulated value based on async resources.
$ npm install p-reduce
import pReduce from 'p-reduce';
import humanInfo from 'human-info'; // Not a real module
const names = [
getUser('sindresorhus').then(info => info.name),
'Addy Osmani',
'Pascal Hartig',
'Stephen Sawchuk'
];
const totalAge = await pReduce(names, async (total, name) => {
const info = await humanInfo(name);
return total + info.age;
}, 0);
console.log(totalAge);
//=> 125
Returns a Promise that is fulfilled when all promises in input and ones returned from reducer are fulfilled, or rejects if any of the promises reject. The fulfilled value is the result of the reduction.
Type: Iterable<Promise|any>
Iterated over serially in the reducer function.
Type: Function
Expected to return a value. If a Promise is returned, it's awaited before continuing with the next iteration.
Type: unknown
Value to use as previousValue in the first reducer invocation.
FAQs
Reduce a list of values using promises into a promise for a value
The npm package p-reduce receives a total of 3,602,907 weekly downloads. As such, p-reduce popularity was classified as popular.
We found that p-reduce demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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