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

Martin Park
Martin Park
12,792 Points

Challenge Working as instructed, but still failing?

Hi,

I'm meant to be highlighting the previous paragraph using previousElementSibling when the highlight button is pressed. I have done this and it works in the preview window but I am still failing?

Wondered if someone could explain why please? Thanks :)

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

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

    let button = event.target;
    let p = button.previousElementSibling;

    let pText = p.textContent;


    p.innerHTML = `<p class="highlight">${pText}</p>`;
  }

});
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

Martin Park
Martin Park
12,792 Points

I had forgotten about className. Still learning :) I guess I completed the challenge in a way that was not predicted, or maybe my original code would cause problems. I read on another answer that previousElementSibling is read-only so you cannot change the value that way, but previousSibling is not read-only. Anyway solved it with the following:

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

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

  let button = event.target;
  let p = button.previousSibling;

    p.className = 'highlight';  

}
});