Asynchronous programming is essential to modern JavaScript development ... nesting and making the code much cleaner and easier to read and maintain. For example, retrieving data from multiple ...

Callbacks were the only natively supported way to deal with async code in JavaScript until ... you start coordinating multiple asynchronous functions. For example, if we wanted to wait two seconds ...

Developers use JavaScript promises to model asynchronous operations ... The essence of this example is that the fetchData() call happens immediately in the code flow, whereas the callback passed ...

If a Tomcat or Jetty server was the upload target, a developer could code a Java ... When an asynchronous JavaScript file upload happens, a server-side component must exist to handle the incoming file ...