var element = document.getElementById('element');
element.classList.add('class-1');
element.classList.add('class-2', 'class-3');
element.classList.remove('class-3');methods: {
onClick(ref) {
const activeClass = 'active-submenu'
if (!this.$refs[ref].classList.length) {
this.$refs[ref].classList.value = [activeClass]
} else {
this.$refs[ref].classList.value = ''
}
},
},var someElement= document.getElementById("myElement");
someElement.className += " newclass";//add "newclass" to element (space in front is important)