Element: classList

const div = document.createElement("div");
div.className = "foo";

//  : <div class="foo"></div>
console.log(div.outerHTML);

//  classList API     
div.classList.remove("foo");
div.classList.add("anotherclass");

// <div class="anotherclass"></div>
console.log(div.outerHTML);

//   "visible"    ,    ,    
div.classList.toggle("visible");

// /  "visible"    ,   
div.classList.toggle("visible", i < 10);

// false
console.log(div.classList.contains("foo"));

//      
div.classList.add("foo", "bar", "baz");
div.classList.remove("foo", "bar", "baz");

//        spread-
const cls = ["foo", "bar"];
div.classList.add(...cls);
div.classList.remove(...cls);

//   "foo"  "bar"
div.classList.replace("foo", "bar");