document.getElementById("myDIV").classList.add("mystyle");
// use the classList API to remove and add classes div.classList.remove("foo"); div.classList.add("anotherclass");
if (document.body.classList.contains('thatClass')) { // do some stuff }
// .classList method returns an array of the classes attached to the element it is called with. document.getElementById("myDIV").classList // It returns // [ 'className1', 'className2', ... ]
//get array of class names in Javascript var classesArray = document.getElementById('myElementID').className.split(/\s+/);