Callback

A callback is a term used in computer programming to describe a piece of code that is passed as an argument to other code. It is also referred to as a “subroutine” or “callback function.” The code passed as an argument is typically executed after the function being called has finished executing. Callbacks are most commonly used in programming to notify a program of the completion of a task, or to perform a certain set of operations after a specific event.

In object-oriented programming languages, a callback is typically an object or method that is passed to a higher-level object to be used as a notification signal. This notification signal can be used notify the program when a certain event has occurred. A common example of this is when a user clicks a button, the user interface (UI) layer of the application will use a callback to notify the backend code that the button was clicked.

In functional programming, a callback is a function that is passed as a parameter to another function. When the receiving function is executed, the callback function is passed to it as an argument and then executed. For example, a map function may be used to iterate over a list and perform a certain action on each element. In this case, the action to be performed on each element is passed as a callback in the map function.

Callbacks are an important feature of many programming languages and can be used to create complex and powerful applications. With the increased use of JavaScript in web development, callbacks have become a very popular way to handle asynchronous code. Callbacks are also used in a variety of other languages, including C, Java, Python, Ruby, and Go.

Overall, callbacks are a fundamental part of programming, and are integral to many programs. While callbacks can be used to create complex applications, they should be handled with care, as they can often introduce errors into a program.