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Jonathan Drake
Full Stack JavaScript Techdegree Student 11,668 PointsNewbie trouble with previousElementSibling Challenge
For the life of me I cannot figure out how to make this work. The whole parentNode thing is still somewhat of a mystery to me, so I'm sure that my difficulty stems from a lack of comprehension of what needs to happen. Using my notes from the previous videos I tried to just apply code I've already seen to what this challenge requires. The error I get is that I'm not selecting a previous sibling. This could also come from not fully understanding the nature of the DOM. As I see it the <button> is a sibling of the <p> which are children of the <li> which is a child of the <ul>... I'm at the point in this unit where I just watch solutions and take lots of notes because I don't have enough of a grasp of the material to improvise. That came later for me in Unit 1...just takes me while. Thanks for any help
var list = document.getElementsByTagName('ul')[0];
list.addEventListener('click', function(e) {
if (e.target.tagName == 'BUTTON') {
let li = e.target.parentNode;
let p = li.previousElementSibling;
let ul = li.parentNode;
if (p) {
ul.className = 'highlight';
}
}
});
<!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>
3 Answers
Stefan Caky
Full Stack JavaScript Techdegree Graduate 14,879 PointsHi. understand the previesElementSibling is not easy. previousElementSibling just select the previous element of any element.. so it means if you select the button element previous element will be the <p> element. if you select the <p> element previous element will be the <li> element. I checked your code and there is a problem that when you do this: let p = li.previousElementSibling; will select the previous <li> element. Not the <p> element. A good answer for this question will be:
list.addEventListener('click', function(e) {
if (e.target.tagName == 'BUTTON') {
let p = e.target.previousElementSibling;
p.className = 'highlight';
}
});
I hope this helped you.
Peter Vann
36,427 PointsHi Jonathan!
This passed for me:
var list = document.getElementsByTagName('ul')[0];
list.addEventListener('click', function(e) {
if (e.target.tagName == 'BUTTON') {
let p = e.target.previousElementSibling;
p.className = "highlight";
}
});
(let p = e.target.previousSibling; passed as well, but I think let p = e.target.previousElementSibling; is better.)
I hope that helps.
Stay safe and happy coding!
Jonathan Drake
Full Stack JavaScript Techdegree Student 11,668 PointsThanks. I was overcomplicating it. This worked perfectly. I was getting tangled up with the parentNode stuff. Still don't fully understand how that works. Just not second-nature yet. Thanks for the reply!
Peter Vann
36,427 PointsHey Stefan!
Jinx!?!
(I didn't plagiarize!?! LOL)
Great minds think alike!
-Pete
:)