Callbacks were the only natively supported way to deal with async code in JavaScript until 2016, when the Promise object was introduced to the language. However, JavaScript developers had been ...

Developers use JavaScript promises to model asynchronous operations ... call happens immediately in the code flow, whereas the callback passed into then() only happens after the asynchronous ...

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. Synchronous programming ...

items.reduce(function(promise, item) { return promise.then(function ... "Writing asynchronous code is hard," it says. "When it comes to JavaScript we rely heavily on callback functions to accomplish ...