How to Add Class in JavaScript: A Guide

JavaScript is one of the most popular programming languages used by web developers today. It is a versatile language that is used to create dynamic and interactive web pages. One of the key features of JavaScript is its ability to add and remove classes from HTML elements. Adding classes to elements is an essential part of creating a dynamic and interactive user interface. In this guide, we will show you how to add class in JavaScript.

Table of Contents

What are Classes in JavaScript?

A class in JavaScript is a blueprint for creating objects. It defines the properties and methods that an object will have. Classes are used to create objects that have the same properties and methods. These objects are referred to as instances of the class.

Classes are an essential part of object-oriented programming in JavaScript. They allow developers to create reusable code that can be used in different parts of their application.

Why Add Class in JavaScript?

Adding classes to HTML elements in JavaScript is essential for creating dynamic and interactive user interfaces. Classes are used to apply styles and manipulate the DOM (Document Object Model) of a web page.

Classes can be used to apply styles to elements based on user interactions. For example, a class can be added to a button element when it is clicked, and the style of the button can be changed to indicate that it has been clicked.

Classes can also be used to show and hide elements on a web page. For example, a class can be added to a div element to hide it, and the class can be removed to show the div element again.

How to Add Class in JavaScript

There are several ways to add class in JavaScript. In this guide, we will show you three common methods.

1. Using the classList Property

The classList property is a built-in property of HTML elements in JavaScript. It allows you to add, remove, and toggle classes on an element.

To add a class to an element using the classList property, you can use the add() method. Here is an example:

const element = document.getElementById("myElement");
element.classList.add("myClass");

In this example, we are selecting an element with the ID "myElement" and adding the class "myClass" to it.

2. Using the className Property

The className property is another built-in property of HTML elements in JavaScript. It allows you to set the class attribute of an element.

To add a class to an element using the className property, you can simply append the class name to the existing class attribute. Here is an example:

const element = document.getElementById("myElement");
element.className += " myClass";

In this example, we are selecting an element with the ID "myElement" and adding the class "myClass" to it.

3. Using the setAttribute() Method

The setAttribute() method is a built-in method of HTML elements in JavaScript. It allows you to set the value of an attribute on an element.

To add a class to an element using the setAttribute() method, you can set the value of the class attribute to the name of the class you want to add. Here is an example:

const element = document.getElementById("myElement");
element.setAttribute("class", "myClass");

In this example, we are selecting an element with the ID "myElement" and setting the class attribute to "myClass".

Conclusion

Adding classes to HTML elements in JavaScript is essential for creating dynamic and interactive user interfaces. Classes are used to apply styles and manipulate the DOM of a web page.

In this guide, we have shown you three common methods for adding classes in JavaScript. These methods include using the classList property, the className property, and the setAttribute() method.

By using these methods, you can add classes to elements and create dynamic and interactive user interfaces for your web applications.

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