Kijek/Adamski's "Slow Light" introduces a man whose eyeballs are so dense that it takes seven years for light to pass through them.

Asynchronous programming in JavaScript leverages features like callbacks, promises and async/await to sidestep this issue by allowing other code to run in the meantime.

Callbacks work fine for handling asynchronous code in JavaScript, but promises and the async and await keywords are cleaner and more flexible.

JavaScript’s async and await functions make for readable and maintainable asynchronous code. Just watch out for their downsides.