var list = document.querySelector('.list');

var button = document.querySelector('.updateList');

​

function updateList(){

    var number = Math.round(Math.random()*100);

    var li = document.createElement('li');

    li.textContent = number;

    list.appendChild(li);

    var lastLi = document.querySelector('.list li:last-child');

    lastLi.scrollIntoView();    

}

​

button.addEventListener('click', updateList);