Callbacks in JavaScript: Why They Exist

In JavaScript function are treated as values just like normal (numbers , string and arrays etc). That means you can : 1. You can store a function in a variable. 2. You can pass it as an argument to another function. 3. You can return a function from another function. What is Callback? : A callback is a function that is passed to another function as an argument and is executed later. It is used to delay the execution of a function. function greet(name, callback) { console.log("Hello " + name); callback(); // calling the callback } function sayBye() { console.log("Bye"); } greet("John", sayBye); Output : Hello John Bye Why callbacks are used in asynchronous programming : Callbacks are used to delay the execution of a function. Scenario: Food Order System : You order food and it takes time to prepare. You give phone number -> call me when ready (callback). Code Example : function orderFood(callback) { console.log("Order placed..."); setTimeout(function() { console.log("Food is ready ")