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

Posted by Skyler Pannekoek
Skyler Pannekoek
8,524 Points

I'm stuck on how to add a className of 'highlight' to a <p> element that's a direct prev sibling of each <button> elemnt

Here’s what I’m given to start with:

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

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

} });

Here’s what I’ve come up with so far. It gives the error message: ‘One or more of the buttons do not affect their previous sibling paragraphs.’

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

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

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

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

1 Answer

Peter Vann
Peter Vann
36,427 Points
Peter Vann
Peter Vann
36,427 Points

Hi Skylar!

Just lose the innerHTML in your code. You don't need it.

This passes:

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

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

I hope that helps.

Stay safe and happy coding!

Skyler Pannekoek
Skyler Pannekoek
8,524 Points

Thanks so much Peter, that worked. Whew - what a relief to finally get that one! :)