A JavaScript callback is a function which is to be executed after another function has finished execution. A more formal definition would be – Any function that is passed as an argument to another function so that it can be executed in that other function is called as a callback function.

What is the need of callback in JavaScript?

Callbacks are a great way to handle something after something else has been completed. By something here we mean a function execution. If we want to execute a function right after the return of some other function, then callbacks can be used. JavaScript functions have the type of Objects.

What is meant by callback?

1 : a return call. 2a : recall sense 5. b : a recall of an employee to work after a layoff. c : a second or additional audition for a theatrical part.