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

Aleksandra Milosavljevic
Aleksandra Milosavljevic
7,100 Points

Sibling traversal

Just wondering why this code won't work and is it,at least, code for getting to the previousElementSibling right? Thanks.

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let li = list.parentNode;
    let p = li.previousElementSibling; 
    p.className = 'hightlight';
  }
});
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>

2 Answers

Steven Parker
Steven Parker
230,231 Points

You're close, but I see a few issues:

  • the parent of the list would be the section
  • you probably want the sibling of the button itself (e.target)
  • you wrote "hightlight" (with an extra "t") instead of "highlight"
Sheila Anguiano
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Sheila Anguiano
Full Stack JavaScript Techdegree Graduate 35,239 Points

I was stuck and I look another student's answer: " if(e.target.textContent.toLowerCase() === 'highlight') { let p = e.target.previousElementSibling; p.classList.add('highlight'); } } });"

That seem to complicated for me, but it help me understand the problem better, which is something similar to this: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_add_class

Thus I came up with my own solution which is just one long line of code in line 5: e.target.previousElementSibling.classList.add(‘highlight’);

Steven Parker
Steven Parker
230,231 Points

Good job :+1: That's probably how I would write it myself.