Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Kevin Horwitz
seal-mask
.a{fill-rule:evenodd;}techdegree
Kevin Horwitz
Full Stack JavaScript Techdegree Student 3,076 Points

Sibling Traversal quiz

I feel live I've done everything correctly. My code is even working in the preview window, but the quiz keeps telling me otherwise

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let p = e.target.previousElementSibling;
    p.classList = 'highlight';   
  }
});
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>

2 Answers

Robert Manolis
STAFF
Robert Manolis
Treehouse Guest Teacher

Hi Kevin, it looks like this is the problem. You can't say p.classList = 'highlight';. ClassList is a collection containing all the classNames. So you could say p.classList.add('highlight');, or probably, p.className = 'highlight';,

Hope that helps. :)