Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Shandale Shelton
Shandale Shelton
7,424 Points
Posted by Shandale Shelton
Shandale Shelton
7,424 Points

Need some assistance.

Not sure what I'm doing wrong.

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

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

2 Answers

Antti Lylander
Antti Lylander
9,686 Points
Antti Lylander
Antti Lylander
9,686 Points

You are very close. You just misspelled Element and you had forgotten a semicolon there and had an extra here.

I don't usually like to give straight answers but as you are so close, here it is:

    let p = e.target.previousElementSibling;
    p.className = 'highlight';
Adam Beer
Adam Beer
11,314 Points
Adam Beer
Adam Beer
11,314 Points

It's a bit more complicated. But the way is good. Add semicolon after to "let p" and delete the extra semicolon.

Challenge Task 1 of 1

A delegated click event listener has been attached to the selected ul element, which is stored in the variable list. The handler is targeting each button in the list. When any one of the buttons is clicked, a class of highlight should be added to the paragraph element immediately preceding that button inside the parent list item element. Add the code to create this behavior on line 5.

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    if(e.target.textContent.toLowerCase() === 'highlight') {
      let li = e.target.parentNode; // Can be removed; not needed
      let p = e.target.previousElementSibling;
      let ul = li.parentNode; // Can be removed; not needed
      if (p.tagName === 'P') { // Just to be safe that we are highlighting a paragraph tag
        p.classList.add('highlight');
      }
    }
  }
});