JS do przyciskow

let elementList = document.querySelector('ul');
let ButtonClickListener = document.querySelector("button");
const node = document.createElement('li');
let number = elementList.lastElementChild.textContent;
ButtonClickListener.addEventListener("click", function () {

    const li = document.createElement('li');
    document.querySelector('ul').appendChild(li).textContent = (++number);
    let tempElement = document.querySelector('ul').lastChild;
    if (parseInt(elementList.lastElementChild.textContent) % 3 == 0) {
        console.log("robie to wieksze");
        li.setAttribute("class", "biggerNumber");
    }
});