Answers for "add class on div using javascript"

js add class

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

javascript add class to element

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

javascript div id add class

var d = document.getElementById("div1");
d.className += " otherclass";