$('.class').addClass() code example
Example: javascript add class
// 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');