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

Preston Hill
Preston Hill
5,766 Points

I do not understand what this challenge is asking me to do. Can anyone help?

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.

app.js
const 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>

1 Answer

Justin Radcliffe
Justin Radcliffe
18,987 Points

Hi Preston,

Looking at the index.html - when any of the buttons is clicked it initiates the callback function in app.js. As it stands, that function isn't doing anything, except checking to see if a button has been clicked.

Inside the if statement you need to apply a class of "highlight" to the paragraph element <p> which is inside the same list item <li> as the clicked button.

The clicked button has already been targeted with:

e.target

So, now i'd target the paragraph element by using:

previousElementSibling // (the element before the button)

and add the class using

className = 'highlight'

I hope this helps you out a little, feel free to get back to me if you need further help.

Preston Hill
Preston Hill
5,766 Points

That worked perfectly. I understand a little more now. Learning this has been really rough for some reason. Thank you so much.