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

Alex L
Alex L
5,024 Points
Posted by Alex L
Alex L
5,024 Points

The <ul> stored in the variable list has a click event listener that targets each <button> in the list.

"The <ul> stored in the variable list has a click event listener that targets each <button> in the list. Complete the code to add a class of highlight to a <p> element that's an immediate previous sibling of the button being clicked."

I am completely baffled.

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let parent = p.parentNode;
    let li = parent.previousElementSibling;
    li.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

Steven Parker
Steven Parker
229,644 Points
Steven Parker
Steven Parker
229,644 Points

You have the right basic idea, but your navigation has gone a little astray. The challenge wants you to "add a class of highlight to a <p> element that's an immediate previous sibling of the button being clicked."

Here's the code from above with a few comments added:

  if (e.target.tagName == 'BUTTON') {       // at this point, e.target is the button
    let parent = p.parentNode;              // this "p" might not next to this button
    let li = parent.previousElementSibling; // we need the button's sibling (not the parent's)
    li.classList.add('highlight');          // we want to highlight the p, not the li
  }

And here's a few hints:

  • you won't need a global "p"
  • navigate to the specific "p" next to the button
  • you won't need to access the parent of the button or paragraph
Alex L
Alex L
5,024 Points
Alex L
Alex L
5,024 Points

Thank you so much for your help :)

Dylan Hamilton
Dylan Hamilton
22,224 Points
Dylan Hamilton
Dylan Hamilton
22,224 Points

I tried this and it did not work for me. Maybe I do not get it.

Steven Parker
Steven Parker
229,644 Points
Steven Parker
Steven Parker
229,644 Points

Dylan, note that the final solution is not shown here, just the code that needed some work. The hints given here might not be the right ones for your own code.

Try starting a fresh question where you can post your own code and get a specific answers for your situation.

Dylan Hamilton
Dylan Hamilton
22,224 Points
Dylan Hamilton
Dylan Hamilton
22,224 Points

I was taking the hint, but got it as I stepped back and thought more about it.