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JavaScript JavaScript and the DOM (Retiring) Traversing the DOM Getting the First and Last Child

Simon Sporrong
Simon Sporrong
35,097 Points

I get: "li.appendChild is not a function" error in the console.

the javascript

const toggleList = document.getElementById('toggleList');
const listDiv = document.querySelector('.list');
const descriptionInput = document.querySelector('input.description');
const descriptionP = document.querySelector('p.description');
const descriptionButton = document.querySelector('button.description');
const addItemInput = document.querySelector('input.addItemInput');
const addItemButton = document.querySelector('button.addItemButton');
const removeItemButton = document.querySelector('button.removeItemButton');
const listItems = document.getElementsByTagName('li')[0];
const listUl = listDiv.querySelector('ul'); 
const lis = listUl.children;
const firstListItem = listUl.firstElementChild;
const lastListItem = listUl.lastElementChild;

lastListItem.style.backgroundColor = 'pink';
firstListItem.style.backgroundColor = 'green';

function attachListItemButtons (li) {
  let up = document.createElement('button');
  up.className = 'up';
  up.textContent = 'Up';
  li.appendChild(up);

  let down = document.createElement('button');
  down.className = 'down';
  down.textContent = 'Down';
  li.appendChild(down);

  let remove = document.createElement('button');
remove.ClassName = 'remove';
  remove.textContent = 'Remove';
  li.appendChild(remove);
}  

for (let i = 0; i < lis.length; i +=1) {
  attachListItemButtons(lis)[i];

}

     listUl.addEventListener('click', (event) => {
 if (event.target.tagName == 'BUTTON') {
   if (event.target.className == "Remove") {
    let li = event.target.parentNode;
    let ul = li.parentNode;
     ul.removeChild(li);

  }
  if (event.target.className == 'up') {
 let li = event.target.parentNode;
  let prevLi = li.previousElementSibling;
    let ul = li.parentNode;
    if (prevLi){
    ul.insertBefore(li, prevLi);
    }
  }


if (event.target.className == 'down'){
  let  li = event.target.parentNode;
  let nextLi = li.nextElementSibling;
  let ul = li.parentNode;
  if (nextLi) {
    ul.insertBefore(nextLi, li);
  }
}
   }
  });


  toggleList.addEventListener('click',() => {
  if (listDiv.style.display == 'none') {
  toggleList.textContent = 'Hide list';
  listDiv.style.display = 'block';
   } else {
  toggleList.textContent = 'Show list';                          
  listDiv.style.display = 'none';
                            } });


  descriptionButton.addEventListener('click', () => {
  descriptionP.innerHTML = descriptionInput.value + ':';
  descriptionInput.value = ' ';
});

    addItemButton.addEventListener('click', () => {
    let ul = document.getElementsByTagName('ul')[0];
    let li = document.createElement('li');
    li.textContent = addItemInput.value;
    attachListItemButtons(li);
    ul.appendChild(li);
    addItemInput.value = '';
  });

and the HTML

<!DOCTYPE html>
<html>
  <head>
    <meta charset = "utf-8">
    <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 id="toggleList">Hide List</button>
    <div class="list">
    <p class="description">Things that are purple:</p>
<input type="text" class="description">
    <button class="description">Change list description</button>

    <ul>
      <li>grapes</li>
      <li>amethyst</li>
      <li>lavender</li>
      <li>plums</li>
    </ul>
      <input type="text" class="addItemInput">
    <button class="addItemButton">Add Item</button>
      <button class="removeItemButton">Remove Item</button>

      </div> 
    <script src="app.js"></script>
  </body>
</html>

This is the uncaught error i get in the console:

Uncaught TypeError: li.appendChild is not a function at attachListItemButtons (app.js:22) at app.js:36

What am I doing wrong? Tried hard to search for typos, you guys see any? Many thanks!

1 Answer

Steven Parker
Steven Parker
229,967 Points

I see a misplaced parenthesis:

About line 36, you have this line:

  attachListItemButtons(lis)[i];

But you probably intended to write this:

  attachListItemButtons(lis[i]);