JavaScript JavaScript and the DOM Traversing the DOM Getting the First and Last Child

DOM Traversal Challenge (solved)

Could anyone please look at my code for the solution of DOM Traversal challenge? Is anything wrong with the quest:

  • Remove up down button if the list element at the top, and remove down button if the list element at the bottom (including when adding new list from the list button);
  • Adding background color to the last and first of the list.
<!DOCTYPE html>
<html>
  <head>
    <title>JavaScript and the DOM</title>
    <link rel="stylesheet" href="css/style.css">
  </head>
  <body>
    <h1 id="myHeading">JavaScript and the DOM</h1>
    <p>Making a web page interactive</p>   
    <button>Hide</button>
    <div id='event_1'> 
    <p class='event_2'>Things that are purple:</p>
    <input type='text' class='event_2'>
    <button class='event_2'>Change the description</button>
    <ul class='addList'>
      <li>grapes</li>
      <li>amethyst</li>
      <li>lavender</li>
      <li>plums</li>
    </ul>
      <input type='text' class='addList'>
      <button class='addList'>List</button>
    </div>
    <script src="script.js"></script>
  </body>
</html>
const buttonPress = document.querySelector('button');
let div = document.getElementById('event_1');
let description = document.querySelector('p.event_2');
let input = document.querySelector('input.event_2');
const button = document.querySelector('button.event_2');

let list = document.querySelector('ul.addList');
const addButton = document.querySelector('button.addList');

let currentList = list.children;

button.addEventListener('click', () => {
                        description.textContent = input.value;
                        });
buttonPress.addEventListener('click', () => {
   if (div.style.display === 'block') {
  buttonPress.innerHTML = 'Show';
  div.style.display = 'none';
} else {
  buttonPress.innerHTML = 'Hide';
  div.style.display = 'block';
}
                             });

function add () {
let textInput = document.querySelector('input.addList').value;
let newList = document.createElement('li');
newList.innerHTML = textInput;
list.appendChild(newList);

  let newButton_2 = document.createElement('button')
newButton_2.innerHTML = 'Up';
newButton_2.className = 'up';
newList.appendChild(newButton_2);

  let newButton_3 = document.createElement('button')
newButton_3.innerHTML = 'Down';
newButton_3.className = 'down';
newList.appendChild(newButton_3);

  let newButton = document.createElement('button')
newButton.innerHTML = 'Remove';
newButton.className = 'remover';
newList.appendChild(newButton);

  list.append(newList);
  //ADD AN ITEM TO THE LIST ALSO APPLY THE CORRECT STYLE

  const removeBottom = parentNode => {
 let top = parentNode.firstElementChild;
 let bottom = parentNode.lastElementChild;
 let previousChild = bottom.previousElementSibling;
 let previousFirst = previousChild.firstElementChild;
 let newButton_2 = document.createElement('button')
newButton_2.innerHTML = 'Down';
newButton_2.className = 'down';
newList.appendChild(newButton_2);
  top.style.backgroundColor = 'lightskyblue';
  bottom.style.backgroundColor = 'lightsteelblue';
  let remove_2 = bottom.querySelector('button.down');
  bottom.removeChild(remove_2);
  previousChild.style.backgroundColor = 'initial';
//Add button down after the previous element  
    previousFirst.after( newButton_2);

}
  removeBottom(list);

}

addButton.addEventListener('click', add);

list.addEventListener('click', (event) => {
  if (event.target.tagName === 'BUTTON') {
    if (event.target.className === 'remover') {
      let li = event.target.parentNode;
      let ul = li.parentNode;
      ul.removeChild(li);
    }
    if (event.target.className === 'up') {
      let li = event.target.parentNode;
      let ul = li.parentNode;
// if use event.target in preLi wrong answer will happen
      let preLi = li.previousElementSibling;
//if preLi !== null so insert Happen      
      if (preLi) {
         ul.insertBefore(li,preLi);

}
    }
     if (event.target.className === 'down') {
      let li = event.target.parentNode;
      let ul = li.parentNode;
      let nextLi = li.nextElementSibling;
      if (nextLi) { 
        ul.insertBefore(nextLi,li);
      }
     }
// REMOVE ALL BUTTONS AND SET BACKGROUND TO INITIAL, THEN ADD
//REMOVE
   let upButtons =document.querySelectorAll('button.up');
for (let i = 0; i < upButtons.length; i++) {
 upButtons[i].parentNode.removeChild(upButtons[i]);
}
 let downButtons =document.querySelectorAll('button.down');
for (let i = 0; i < downButtons.length; i++) {
 downButtons[i].parentNode.removeChild(downButtons[i]);
} 
 let removeButtons =document.querySelectorAll('button.remover');
for (let i = 0; i < removeButtons.length; i++) {
 removeButtons[i].parentNode.removeChild(removeButtons[i]);
} 
for (let i = 0; i < currentList.length; i++) {
  currentList[i].style.backgroundColor = 'initial';
}
//ADD ALL BUTTONS IN LISTS
    addButtons(currentList)
//ADD AND REMOVE BUTTONS AT FIRST AND LAST LISTS FOLLOWING THE INSTRUCTION OFTHE QUEST
  const removeTop_Bottom = parentNode => {
 let top = parentNode.firstElementChild;
 let bottom = parentNode.lastElementChild;
  top.style.backgroundColor = 'lightskyblue';
  bottom.style.backgroundColor = 'lightsteelblue';
  let remove_1 = top.querySelector('button.up');
  let remove_2 = bottom.querySelector('button.down');
  top.removeChild(remove_1);
  bottom.removeChild(remove_2);
  }
removeTop_Bottom(list);  
  }
  });
const addButtons = list => {
 for (let z = 0; z < list.length; z++) {
        let newButton_2 = document.createElement('button')
newButton_2.innerHTML = 'Up';
newButton_2.className = 'up';

  let newButton_3 = document.createElement('button')
newButton_3.innerHTML = 'Down';
newButton_3.className = 'down';

  let newButton = document.createElement('button')
newButton.innerHTML = 'Remove';
newButton.className = 'remover';
   list[z].append(newButton_2, newButton_3, newButton);
 }
}
addButtons(currentList);

const removeTop_Bottom = parentNode => {
 let top = parentNode.firstElementChild;
 let bottom = parentNode.lastElementChild;
  top.style.backgroundColor = 'lightskyblue';
  bottom.style.backgroundColor = 'lightsteelblue';
  let remove_1 = top.querySelector('button.up');
  let remove_2 = bottom.querySelector('button.down');
  top.removeChild(remove_1);
  bottom.removeChild(remove_2);

}
//INITIAL SETTING FOR UL ELEMENT WHEN THE BROWSER LOADS
removeTop_Bottom(list);