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

Posted by Paul Harvey
Paul Harvey
17,321 Points

Sibling Traversal: Can't figure out how to attach the class

Well, I'm stuck. As the JS classes have gotten more and more difficult, it feels like it's harder to figure out the solution from the previous videos.

Someone better at this than I am, please review my code and figure out how to make it work?

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

list.addEventListener('click', function(event) {
  if (event.target.tagName == 'BUTTON') {
    let button = event.target.parentNode;
    let para = button.previousElementSibling;
    para.classList.add('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

Emmanuel C
Emmanuel C
10,636 Points
Emmanuel C
Emmanuel C
10,636 Points

Hi,

event.target is actually the button element. When you call parentNode you're actually getting the li element the button is in, then the previousSibling on the li would be another li, depending on which button you press. So setting that button var to just the event.target would fix this.

let button = event.target;
Paul Harvey
Paul Harvey
17,321 Points
Paul Harvey
Paul Harvey
17,321 Points

Oh my gosh, what a silly mistake! I totally overlooked that.

It's working now, many thanks!