javascript if this has class code example

Example 1: javascript check if element has class

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

Example 2: javascript hass class

if (myElement.classList.contains('someClassname')) {
    // do something
}

Example 3: check if a class exists javascript

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

element.classList.contains("active");