JavaScript JavaScript and the DOM Traversing the DOM Sibling Traversal

Olivia Wyatt
Olivia Wyatt
Full Stack JavaScript Techdegree Student 4,372 Points

I can't figure out how to select the previous sibling of all the buttons.

I tried simply selecting the previous sibling of the of the button clicked by doing event.target.previousElementSibling then assigning a class name to that but the error that popped up said one or more of the buttons were not selected. Then I tried looping through the buttons and selecting the previous sibling of each button individually. Still getting the same error. Any help would be greatly appreciated! Thanks in advance!

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let button = document.getElementsByTagName('button');
    for(let i = 0; i < button.length; i++) {
      let prevSib = button[i].previousElementSibling;
      prevSib.className = "hightlight";
    }

  }
});
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

Steven Parker
Steven Parker
200,589 Points

You're close, but have a few issues:

  • you don't need a loop, you only need to highlight the one paragraph next to the clicked button
  • the provided code has already determined that "e.target" is the button, you don't need a select function
  • the class name to be assigned is "highlight" (with only one "t"), not "hightlight"