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JavaScript JavaScript and the DOM (Retiring) Traversing the DOM Sibling Traversal

vincent batteast
vincent batteast
51,094 Points

A delegated click event listener has been attached to the selected ul element, which is stored in the variable list. The

this is the error that I'm getting

Bummer! One or more of the buttons do not affect their sibling paragraphs.

app.js
const list = document.getElementsByTagName('ul')[0];

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let  li = document.getElementsByTagName("li");
    let ul = li.parentNode; 
    let nli = li.previousElementSibling;
     if (e.target.tagName === 'Highlight') {
        list.insertBefore(nli, li);
      }
  }
});
index.html
<!DOCTYPE html>
<html>
    <head>
        <title>JavaScript and the DOM</title>
    </head>
    <link rel="stylesheet" href="style.css" />
    <body>
        <section>
            <h1>Making a Webpage Interactive</h1>
            <p>Things to Learn</p>
            <ul>
                <li><p>Element Selection</p><button>Highlight</button></li>
                <li><p>Events</p><button>Highlight</button></li>
                <li><p>Event Listening</p><button>Highlight</button></li>
                <li><p>DOM Traversal</p><button>Highlight</button></li>
            </ul>
        </section>
        <script src="app.js"></script>
    </body>
</html>

1 Answer

Steven Parker
Steven Parker
229,982 Points

You need to navigate from the event target.

When you call getElementsByTagName you get a collection instead of a single element, and a collection does not have a parentNode property. But more importantly, you need to traverse the DOM starting with the event target to be sure you eventually change the class of the correct paragraph based on which button was clicked.

And remember that "Highlight" is a class name, not a tag name. You'll be adding this class name to an existing element, you won't need to add any new elements.