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

Nick Retel
Nick Retel
Courses Plus Student 4,516 Points

e.target.previousSibling.className += " highlight"; affects all buttons / p elements why is this not correct?

Why is this code not correct according to Teamtreehouse? It works as expected:

e.target.previousSibling.className += " highlight";

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    e.target.previousSibling.className += " highlight";
<!DOCTYPE html>
        <title>JavaScript and the DOM</title>
    <link rel="stylesheet" href="style.css" />
            <h1>Making a Webpage Interactive</h1>
            <p>Things to Learn</p>
                <li><p>Element Selection</p><button>Highlight</button></li>
                <li><p>Event Listening</p><button>Highlight</button></li>
                <li><p>DOM Traversal</p><button>Highlight</button></li>
        <script src="app.js"></script>

2 Answers

Hi Nick,

The tester doesn't want the space you have before highlight.

I think your intention was to add the class to what is already there, making sure there's a space.

You should assume that the class should be set to "highlight" only.

Nick Retel
Nick Retel
Courses Plus Student 4,516 Points

Yeah you are correct. "Add a highlight class" made me think I had to add an additional class. Got it sorted now.