Understanding “this” Keyword in JavaScript

JavaScript, a dynamic programming language, offers various features that can sometimes be confusing, especially for beginners. One such feature is the ‘this’ keyword. This article aims to demystify the use of ‘this’ in JavaScript, providing clear examples to enhance understanding.

What is ‘this’ in JavaScript?

In JavaScript, ‘this’ is a keyword that refers to the object it belongs to. This context-based keyword has different values depending on where it is used. Whether in a function, an object method, or alone, ‘this’ can have various meanings.

‘this’ in Global Context

When used in the global context, outside of any function, ‘this’ refers to the global object. In a web browser, the global object is window, whereas in Node.js, it’s global.

console.log(this === window); // true in a web browser

‘this’ Inside a Function

In a regular function, the value of ‘this’ depends on how the function is called. If the function is called as a method of an object, ‘this’ refers to the object. However, in a regular function call, ‘this’ refers to the global object (or undefined in strict mode).

function myFunction() {

myFunction(); // 'this' will refer to the global object or 'undefined' in strict mode

‘this’ with Arrow Functions

Arrow functions do not have their own ‘this’ binding. Instead, they inherit ‘this’ from the parent scope at the time of definition.

const myObject = {
  myMethod: () => {

myObject.myMethod(); // 'this' refers to the parent scope, not 'myObject'

‘this’ in Event Handlers

In the context of DOM event handlers, ‘this’ refers to the element that received the event.

document.getElementById("myButton").addEventListener("click", function() {
  console.log(this); // 'this' refers to the element with id 'myButton'

Manipulating ‘this’ with call, apply, and bind

JavaScript provides methods like call, apply, and bind to set the value of ‘this’ explicitly.

function greet() {
  console.log(`Hello, ${this.name}`);

const person = { name: 'Alice' };

greet.call(person); // Explicitly sets 'this' to 'person'

Common Pitfalls and Best Practices

Understanding ‘this’ is crucial for avoiding common pitfalls in JavaScript coding. It’s essential to be aware of the context in which ‘this’ is used, especially in callbacks and event handlers.


What is the ‘this’ keyword in JavaScript?

‘This’ in JavaScript is a context-based keyword that refers to the object it belongs to, varying based on its usage in different parts of the code.

How do you use ‘this’ in JavaScript?

‘This’ can be used in various contexts in JavaScript, such as in functions, methods, event handlers, and with call, apply, and bind methods to refer to different objects based on the execution context.

Why is ‘this’ in JavaScript undefined in arrow functions?

In arrow functions, ‘this’ is not bound to its own context but inherits from the parent scope. Thus, it remains undefined within the arrow function’s own scope.

Can the value of ‘this’ be changed in JavaScript?

Yes, the value of ‘this’ can be explicitly set in JavaScript using methods like call, apply, and bind.


Mastering the ‘this’ keyword in JavaScript is a step toward writing more efficient and cleaner code. By understanding the context in which ‘this’ operates, developers can avoid common errors and utilize JavaScript’s full potential.

Leave a Comment