venilla javascript .classList add class code example

Example 1: css class list

var myElement = document.getElementById("myElementID");
myElement.classList.add("style1 style2");
myElement.classList.remove("style1 style2");

Example 2: add to classlist javascript

Add multiple classes to a 
 element:
document.getElementById("myDIV").classList.add("mystyle", "anotherClass", "thirdClass");

Remove a class from a 
 element:
document.getElementById("myDIV").classList.remove("mystyle");

Remove multiple classes from a 
 element:
document.getElementById("myDIV").classList.remove("mystyle", "anotherClass", "thirdClass");

Toggle between two classes for a 
 element:
document.getElementById("myDIV").classList.toggle("newClassName");

Find out if an element has a "mystyle" class:
document.getElementById("myDIV").classList.contains("mystyle");