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

There was an error with your code: TypeError: 'undefined' is not an object (evaluating '_p.previousElement.Sibling')


Any idea to crack it?

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

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

    let p = event.target.parentNode;
    let prevP = p.previousElement.Sibling;

    if (prevLi) {
    let ul = insertBefore(prevP,p);


    p.highlight = p.highlight.style.background.green
<!DOCTYPE html>
        <title>JavaScript and the DOM</title>
    <link rel="stylesheet" href="style.css" />
            <h1>Making a Webpage Interactive</h1>
            <p>Things to Learn</p>
                <li><p class = 'highlight'>Element Selection</p><button>Highlight</button></li>
                <li><p class = 'highlight'>Events</p><button>Highlight</button></li>
                <li><p class = 'highlight'>Event Listening</p><button>Highlight</button></li>
                <li><p class = 'highlight'>DOM Traversal</p><button>Highlight</button></li>
        <script src="app.js"></script>

2 Answers

Hey jc laurent,

Add this inside your if code block: e.target.previousElementSibling.className = "highlight";

Your final code should look like this:

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

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

Happy Coding!