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

Treehouse thinks my answer is wrong, console says otherwise

Challenge is to make code that when the button is clicked, add the class "highlight" to the previous sibling, however with the code provided here, Treehouse gives me the following error when trying to check my work:

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

any idea what's up? Any help is appreciated! :)

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
   e.target.previousElementSibling.addClassName = "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

Can you provide a reference for addClassName? I found one article on stack overflow. It should just be className.

Yup. Should have been className, my mistake! Thanks :)