Add a Class to an Element

To add a class to an element, you use the classList property of the element. Suppose you have an element as follows:

<div>Item</div>Code language: HTML, XML (xml)

To add the box class to the <div> element, you use the following:

const div = document.querySelector('div');
div.classList.add('box');Code language: JavaScript (javascript)

It’s possible to add multiple classes. The following adds three classes to the <div> element:

const div = document.querySelector('div');
div.classList.add('box','primary','rounded');Code language: JavaScript (javascript)