change icon classlist button code example

Example 1: add multiple class list at once in js

elem.classList.add("first");
elem.classList.add("second");
elem.classList.add("third");

is equal to :

elem.classList.add("first","second","third");

Example 2: css class list

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