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

Pilar Fernandez
Pilar Fernandez
3,085 Points
Posted by Pilar Fernandez
Pilar Fernandez
3,085 Points

I'm not sure how to select the p and button elements from the same list element using parentNode

I need to select the button so when the user clicks on it, it adds the class to the sibling paragraph element, but I don't know how to select them using parentNode.

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let btn = p.nextElementSibling;
    if(btn){
      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

tobiastrinkler
.a{fill-rule:evenodd;}techdegree
tobiastrinkler
Full Stack JavaScript Techdegree Student 16,538 Points

Hi Pilar,

Since you have to use DOM Traversal you should not create an extra variable to grab onto the paragraph element on the page. When you look at the HTML code you can see that the button and paraghraph element are siblings. You can also see that paragraph element comes before the button which means in our handler we can use the previousElementSibling method to grab onto the paragraph element when a button is clicked.

Hope I could help you out with this :).

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

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

  }
});
Pilar Fernandez
Pilar Fernandez
3,085 Points
Pilar Fernandez
Pilar Fernandez
3,085 Points

Thank you Tobias Trinkler !!! It was way simpler than what I was doing lol