What Are Callbacks in JavaScript?

What Are Callbacks in JavaScript?

A callback is a function that is passed as an argument to another function and executed later.

Callbacks are one of the foundations of asynchronous JavaScript.

Example

function greet(name, callback) {
  console.log("Hello " + name);
  callback();
}

The callback function runs after the main operation.

Why Are Callbacks Useful?

Callbacks help developers:

• Execute Code Later
• Handle Asynchronous Operations
• Improve Reusability
• Create Flexible Functions

Common Use Cases

Callbacks are used in:

• Event Handlers
• API Requests
• Timers
• Array Methods

Callbacks and Asynchronous JavaScript

Before Promises and Async/Await became popular, callbacks were the primary way to handle asynchronous operations.

Understanding callbacks remains important because they form the foundation of modern asynchronous programming.

Learn Async JavaScript Deeply

Callbacks, Event Loop, Promises, and Async/Await are closely connected concepts.

Namaste JavaScript explains how callbacks interact with the Event Loop and browser APIs, helping learners understand asynchronous JavaScript from first principles.

The Bottom Line

A callback is a function passed into another function to be executed later. Callbacks are a fundamental building block of JavaScript programming.