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JavaScript JavaScript and the DOM (Retiring) Traversing the DOM Using parentNode to Traverse Up the DOM

Modou Sawo
Modou Sawo
13,141 Points
Posted by Modou Sawo
Modou Sawo
13,141 Points

I get a TypeError when I try to remove the list items using parentNode & event.target by clicking....

I get this message saying, "Uncaught TypeError: Cannot read property 'removeChild' of undefined" ==> pointing at the ul.removeChild(li); line 15.

HTML code:

<!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 id="toggleList">Hide list</button>
    <div class="list">
      <p class="description">Things that are purple:</p>
      <input type="text" class="description">
      <button class="decription">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 last item</button>
    </div>

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

Here's my JS code:

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');


listDiv.addEventListener('click', (event) => {
  if (event.target.tagName == 'LI') {
    let li = event.target;
    let ul = event.parentNode;
    ul.removeChild(li);
  }
});

1 Answer

miikis
miikis
44,957 Points

Hey Modou,

Your reference to the unordered list is incorrect. The unordered list is the parent node of the list item — not the parent node of the Event object. Try const ul = li.parentNode. That'll make it work for ya.

Modou Sawo
Modou Sawo
13,141 Points
Modou Sawo
Modou Sawo
13,141 Points

Hi Mikis, Thanks man! It worked.

While here, can you please look at line 51, I get a "Uncaught TypeError: Cannot read property 'addEventListener' of null": 

removeItemButton.addEventListener('click', () => {
  let ul = document.getElementsByTagName('ul')[0];
  let li = document.querySelector('li:last-child');
  ul.removeChild(li);
})

descriptionButton.addEventListener('click', () => {
  descriptionP.innerHTML = descriptionInput.value + ':';
});
miikis
miikis
44,957 Points

You're welcome sir. You've probably figured it out by now but the reason that addEventListener isn't attaching to descriptionButton is because you have a typo: in your HTML, you spelled the button's class-name wrong. Fix that and it'll work ;)