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

Posted by Kylie Soderblom
Kylie Soderblom
3,890 Points

add a class of highlight to a <p> element that's an immediate previous sibling of the button

I'm at a loss. I can get the parent Node of the e target. let parent = e.target.parentNode; prevSib = parent.previousElementSibling; p= document.query(prevSib p); I think. and I can change p.className = "highlight"; But I'm missing something. I don't really understand how to target the <p> element inside the parent.

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

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

  }
});
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>

3 Answers

Peter Vann
Peter Vann
36,427 Points

Hi Kylie!

I hope this helps you visualize it:

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    // then you want to target the previous element sibling
    // of e.target (because that's the current button element)
    // and give that element the class "highlight"
  }
});

Which would look like this:

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

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

And passes!

I hope that helps.

Stay safe and happy coding!

Kylie Soderblom
Kylie Soderblom
3,890 Points
Kylie Soderblom
Kylie Soderblom
3,890 Points

Your timing! lol. I just took a new approach. Sometimes it helps to look at it from another direction. let p = e.target.previousElementSibling; p.className = "highlight";
I like your concise solution even better!

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

Hey Kylie!

Thanks for the "attaboy"/kudos - I appreciate it.

Your solution is not inferior, though.

Sometimes adding the variable assignment, as you used, can actually make the code more readable.

(Especially when/since DOM transversal syntax is SO BLOODY LONG!?! LOL)

The important thing is that you understand it and can use it in the real world, which evidently you got!!!

:)

I hope that helps.

Stay safe and happy coding!