Promises vs Async callbacks

Promises and async callbacks are both ways to handle asynchronous operations in JavaScript, but they work in slightly different ways.

Async callbacks: In JavaScript, callbacks are functions that are passed as arguments to other functions, and are called when an operation is completed. For example, when making an HTTP request, you might pass a callback function that is called when the response is received. Callbacks can be used to handle asynchronous operations, but they can lead to callback hell, which can make code hard to read and maintain.

Promises: Promises were introduced in ECMAScript 6 as a way to handle asynchronous operations in a more readable and maintainable way than callbacks. A promise is an object that represents the eventual completion (or failure) of an asynchronous operation, and allows you to attach callbacks to handle those outcomes. Promises have three states: pending, fulfilled, or rejected.

Here are some key differences between promises and async callbacks:

1. Promises can be chained together using the .then() method, which makes it easy to perform multiple asynchronous operations in sequence.

2. Promises have a .catch() method, which allows you to handle errors in a more readable way than try-catch blocks with async callbacks.

3. Promises are composable, meaning you can pass them around like any other value, whereas async callbacks require the use of a function to handle the callback.

In summary, while both promises and async callbacks are ways to handle asynchronous operations in JavaScript, promises provide a cleaner and more maintainable approach that makes it easier to reason about your code.