async is all present in JavaScript for two reasons:- you make network requests all the time
- JavaScript is single threaded, so if you are waiting for a network request, the UI freezes, see remarks on the deprecation of synchronous HTTP request at: developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Synchronous_and_Asynchronous_Requests
However, it is also Hell: how to convert
async to sync in JavaScript. New to topics? Read the docs here!