addclass javascript

var element = document.getElementById('element');
element.classList.add('class-1');
element.classList.add('class-2', 'class-3');
element.classList.remove('class-3');

var element = document.getElementById("myDIV");
// to add
element.classList.add("mystyle");
// to remove
element.classList.remove("mystyle");

// getting the target element
var myElement = document.querySelector('#myElement');

// example for addding some-class to the element
myElement.classList.add('some-class');

// multiple classes can be added like this
myElement.classList.add('one-class', 'one-more-class');

// example for removing any class from the element
myElement.classList.remove('any-class');

var someElement= document.getElementById("myElement");
    someElement.className += " newclass";//add "newclass" to element (space in front is important)

const addClass = (element, name) => {
    const arr = element.className.split(" ");
    if (arr.indexOf(name) === -1) {
        element.className += " " + name;
    }
};