To add a CSS class to an HTML element, you can use the classList property of the element. It is a read-only property that returns a live DOMTokenList collection of all the classes applied to the element.

Let us say you have the following HTML element:

<div>🍕</div>

To add the pizza class to the above <div> element, you can use the following code:

const div = document.querySelector('div');

div.classList.add('pizza');

The classList.add() method also allows you to add multiple classes:

const div = document.querySelector('div');

div.classList.add('pizza', 'spice', 'potato');

The classList property only works in modern browsers, and IE10 and above.

Take a look at this article to learn more about adding, removing, and toggling CSS classes in JavaScript.

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