PW10.4.1.JS

// this code is my attempt at answer to question 1, I am not sure why it is not working
var apple = document.getElementsByClassName('current');
for ( i=0; i<apple.length; i++) {
  document.getElementsByClassName('current').className = 'finished';
  
}
document.getElementById('next').className = 'current';
document.getElementById('next').removeAttribute('id');
document.getElementsByTagName('li')[3].setAttribute('id', 'next');
var addCool = function() {
  var listNum = document.getElementsByTagName('li').length;
  for (i=0; i < listNum; i++) {
    document.getElementsByTagName('li')[i].setAttribute('class', 'cool');
  }
};
document.getElementById('chill').addEventListener('click',addCool);
var addLi = function () {
  var newListItem = document.createElement('li');
  newListItem.textContent = 'Javascript';
  document.getElementsByTagName('li')[4].appendChild(newListItem);
}
document.getElementsByTagName('li')[0].addEventListener('click',addLi);