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

aliceinwonderland
aliceinwonderland
7,679 Points
Posted by aliceinwonderland
aliceinwonderland
7,679 Points

I googled this and came up with the solution of: element.classList.add("name-of-class"); several times.

Please prompt me on where to start.

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    p.classList.add("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>

1 Answer

I Dilate
I Dilate
3,983 Points
I Dilate
I Dilate
3,983 Points

Hey again Alice,

So in this challenge, they want you to add a className of "highlight" to the <p> that sits next to the <a> that has been clicked.

We can just use e.target to select the element that has been clicked (the button), but then we need to add something to select the <p> that sits next to it.

In the lessons, do you remember being introduced to the idea of a parent, child and sibling?

Well if the <p> is sat next to the <a> (not one inside the other, or in a layer above or below each other) then they are known as siblings. Imagine it like a family tree - the <a> is the brother/sister of the <p> if they're inside the same element (their parents).

So because the <p> comes before the <a> - we can use .previousElementSibling to select it!

Here's a solution:

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

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