AsynchronousLesson 11Free preview

Node Promises

This lesson is part of Node.js · All levels

Summary

A promise is an object that represents a value that is not yet available in the future: pending, fulfilled, or rejected. With Promise, the asynchronous chain of operations can be written more neatly using then, catch, and finally. Methods like all and race even allow for running many promises in parallel.

Key points

Promises have three status: pending, fulfilled, and rejected
Then handle the successes, catch handle the errors, finally run in both cases.
Promise.all waiting for all success; allSettled waiting for all finished with its status
Promise to avoid callback hell thanks to a flatter chain then

Full lesson

Code examples and quizzes

Full lessons, code examples, and quizzes are available to subscribers. 5 questions.