2021-11-08
2621
#vanilla javascript
Fernando Doglio
4429
Nov 8, 2021 â‹… 9 min read

JavaScript Promises: race, all, allSettled, and then

Fernando Doglio Technical Manager at Globant. Author of books and maker of software things. Find me online at fdoglio.com.

Recent posts:

Stagehand and Gemini logos on a gradient background symbolizing AI web automation

How to build a web-based AI agent with Stagehand and Gemini

This guide walks you through creating a web UI for an AI agent that browses, clicks, and extracts info from websites powered by Stagehand and Gemini.

Elijah Asaolu
Jul 4, 2025 â‹… 8 min read
Getting Started With Claude 4 API: A Developer's Walkthrough

Getting started with Claude 4 API: A developer’s walkthrough

This guide explores how to use Anthropic’s Claude 4 models, including Opus 4 and Sonnet 4, to build AI-powered applications.

Andrew Baisden
Jul 3, 2025 â‹… 16 min read
ai dev tool power rankings

AI dev tool power rankings & comparison [July 2025 edition]

Which AI frontend dev tool reigns supreme in July 2025? Check out our power rankings and use our interactive comparison tool to find out.

Chizaram Ken
Jul 2, 2025 â‹… 3 min read
how API client automation can save you hours in development

How API client automation can save you hours in development

Learn how OpenAPI can automate API client generation to save time, reduce bugs, and streamline how your frontend app talks to backend APIs.

Lewis Cianci
Jul 1, 2025 â‹… 7 min read
View all posts

3 Replies to "JavaScript Promises: race, all, allSettled, and then"

  1. Mozilla’s web documentation at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all has an good workaround for the problem of rejection stopping Promise.all(). I have been using it without any issues so far:

    var p1 = new Promise((resolve, reject) => {
    setTimeout(() => resolve(‘p1_delayed_resolution’), 1000);
    });

    var p2 = new Promise((resolve, reject) => {
    reject(new Error(‘p2_immediate_rejection’));
    });

    Promise.all([
    p1.catch(error => { return error }),
    p2.catch(error => { return error }),
    ]).then(values => {
    console.log(values[0]) // “p1_delayed_resolution”
    console.log(values[1]) // “Error: p2_immediate_rejection”
    })

  2. Nice article, but one thing should be noted. You say:

    “By definition,Promise.all will run all your promises until one of the following conditions are met:”

    It’s not true. Promise.all doesn’t run anything. Promises are ALWAYS fired immediately, always. There are no methods to explicitly control Promise’s execution. Promise.all just listens their execution, but doesn’t do anything else.

Leave a Reply