How does async/await work?

The async/await construct is convenient syntactic sugar over standard Promises that allows you to write asynchronous code as if it were synchronous, significantly simplifying its reading and maintenance. Any async function always automatically returns a Promise, even if the return operator is not explicitly specified inside it. This guarantees that calling code can always continue the chain via the then method or use the await keyword.

The key element of this syntax is the await operator, which can only be used inside async functions. When the interpreter reaches a line with await, it pauses the execution of the current function and waits for the specified promise to resolve, freeing up the thread to execute other tasks in the event loop. As soon as the promise successfully resolves, function execution resumes, and the promise value is assigned to a variable, saving the developer from having to write many nested callback functions.

For example, when developing client applications, you can sequentially send requests to the server, waiting for a response from each in a clear linear structure. At its core, async/await does not introduce fundamentally new capabilities to the JavaScript engine, but it radically changes the approach to writing code, reducing the likelihood of errors due to the natural sequence of steps and simplifying the debugging of complex asynchronous algorithms.