JS Promise

Creator

Creator

Seonglae Cho

Created

Created

2020 Feb 21 4:22

Editor

Editor

Seonglae Cho

Edited

Edited

2025 Oct 6 9:32

Refs

Refs

An object containing a state [[PromiseStatus]] and a value [[PromiseValue]]

Enables writing intuitive asynchronous code when used with async/await. It was developed to address the poor readability of deeply nested callbacks. With callbacks, asynchronous operations must be nested, making exception handling difficult and reducing code readability.

JS Promise.all() doesn't provide information about which promises failed, so we need to retry the entire list when it fails. However,

JS Promise.allSettled() shows which promises succeeded or failed, allowing us to retry only the specific failed requests.

JS Promise Notion

JS PromiseStatus

JS PrimiseValue

JS Promise Function

JS Promise Usages

js try/catch/finally

JS unhandled promise

top level await

JS Promise.all()

JS Promise.allSettled()

JS Promise.any()

JS Promise.race()

⭐️🎀 JavaScript Visualized: Promises & Async/Await

If you're here in 2024 (or later), here's an updated video: Ever had to deal with JS code...

⭐️🎀 JavaScript Visualized: Promises & Async/Await

https://dev.to/lydiahallie/javascript-visualized-promises-async-await-5gke

⭐️🎀 JavaScript Visualized: Promises & Async/Await

This article was originally written as an answer on Stack Overflow. The hope is that by seeing how you would go about implementing Promise in JavaScript, you may gain a better understanding of how promises behave.

https://www.promisejs.org/implementing/

Implement a Simple Promise in Javascript

In front-end engineering interviews and daily front-end development, we encounter Promises all the time. In these interviews, I have been…

Implement a Simple Promise in Javascript

https://medium.com/swlh/implement-a-simple-promise-in-javascript-20c9705f197a

Implement a Simple Promise in Javascript

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