if class exists js code example

Example 1: javascript check if element has class

if(document.getElementById("myElmentID").classList.contains("hidden")){
// I have the 'hidden' class
}

Example 2: check if a class exists javascript

const element = document.querySelector("#box");

element.classList.contains("active");

Example 3: check if a class exists javascript

<div id="box" class="active"></div>