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Write a function which receives a string, and returns a Promise. The promise should resolve with the uppercase version of the string, but should reject if the string is null. learn-js.org is a free interactive JavaScript tutorial for people who want to learn JavaScript, fast.
Jun 23, 2024 · A Promise object serves as a link between the executor (the “producing code” or “singer”) and the consuming functions (the “fans”), which will receive the result or error. Consuming functions can be registered (subscribed) using the methods .then and .catch.
Apr 9, 2024 · So, what are promises in JavaScript? A promise is an object that represents the eventual completion or failure of an asynchronous operation. You create that object with the new Promise() constructor.
Promises are a way to write asynchronous code that is easier to read and debug. They are also a way to handle errors in asynchronous code without having to use try/catch blocks. A promise can be in one of three states: pending, fulfilled, or rejected.
Sep 8, 2023 · Promises are a powerful tool in JavaScript that help manage asynchronous operations and provide a more readable and maintainable codebase. In this tutorial, we will take you from a beginner's level to an expert level, covering all the important aspects of JavaScript promises.
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Jun 13, 2023 · Working with promises is a very useful skill every JavaScript developer should learn. This article is an in-depth guide to promises in JavaScript. You are going to learn why JavaScript has promises, what a promise is, and how to work with it. You are also going to learn how to use async/await—a feature derived from promises—and what a job queue is.
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May 25, 2022 · JavaScript Promises for Beginners. Spruce Emmanuel. In JavaScript, a promise is a placeholder (proxy) for the value of an ongoing operation. You typically use a promise to manage situations where you must wait for the outcome of an operation.
