Async/await
As we have just seen, promises are a quantum leap ahead of callbacks. They allow us to write clean and readable asynchronous code and provide a set of safeguards that can only be achieved with boilerplate code when working with callback-based asynchronous code. However, promises are still suboptimal when it comes to writing sequential asynchronous code. The Promise chain is indeed much better than having callback hell, but still, we have to invoke a then() and create a new function for each task in the chain. This is still too much for a control flow that is definitely the most commonly used in everyday programming. JavaScript needed a proper way to deal with the ubiquitous asynchronous sequential execution flow, and the answer arrived with the introduction in the ECMAScript standard of async functions and the await expression (async/await for short).
The async/await dichotomy allows us to write functions that appear to block at each asynchronous operation, waiting...