If you’ve had the chance to observe modern JavaScript code, there are high chances that you’ve seen the async and await syntax somewhere.

Async/await is arguably one of the best-received new additions to the language. Async/await makes the asynchronous code appear and behave like synchronous code. Async/await are promise-based.

Before we jump into async/await, we must understand what promises are and the role they play.

Promises

A Promise is an object representing the eventual completion or failure of an asynchronous operation.

Why do we need the asynchronous code, anyway?

JavaScript is a single-threaded language — which means JavaScript can only do one thing at once. Imagine calling our API synchronously and blocking the entire thread for the API call duration — our users would have to wait 30 seconds or as long it takes for the network request to resolve — a big no-no!

In case you’re interested to learn more — here’s a more in-depth explanation about asynchronous programming with JavaScript.

The way we used to handle asynchronous JavaScript code was via callbacks. Chances are high that you’ve come across callbacks.

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