Promise For The Newby, How Promises Works in Javascript

What is a Promise?

A Promise is an object that represents the eventual completion or failure of an asynchronous operation and its resulting value. A Promise is used to handle asynchronous operations and provide a way to avoid callback hell.

A Promise can be in one of three states:

1. Pending: The initial state. The promise is neither fulfilled nor rejected.
2. Fulfilled: The operation completed successfully, and the promise has a resulting value.
3. Rejected: The operation failed, and the promise has a reason for the failure.

Creating a Promise

To create a Promise in JavaScript, you use the Promise constructor. The constructor takes a single argument: a function called the “executor” function. The executor function takes two parameters: “resolve” and “reject”. These are functions that you call to change the Promise’s state.

Here’s an example of creating a Promise that resolves with a value after a delay:

const promise = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve('Hello, world!');
  }, 1000);
});

In this example, the Promise will resolve with the string “Hello, world!” after a delay…