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

Posted by seongho kang
seongho kang
3,877 Points

I need your help to solve this Task.

I don't get this is not working well. Which one did i miss for solving this task?

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

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    let p = e.target.parentNode;
    let prevP = p.previousElementSibling;
    let li = p.parentNode;
    if (prevP) {
        li.insertBefore(p, prevP);      
    }
  }
});
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
231,269 Points
Steven Parker
Steven Parker
231,269 Points

Here's some hints:

  • you want to target the sibling of the button, not the sibling of the button's parent.
  • you don't need to move any element positions
  • just give the sibling paragraph a new class attribute ("highlight")
Daniel Baker
Daniel Baker
15,369 Points
Daniel Baker
Daniel Baker
15,369 Points 
var list = document.getElementsByTagName('ul')[0];

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

    let p = e.target.parentNode; // This will actually be the <li>, the <p>is a sibling not the parent
    let prevP = p.previousElementSibling; //this will attempt to be the previous sibling of <li>
    let li = p.parentNode; //this will be the <ul>
    if (prevP) { 
        li.insertBefore(p, prevP);      
    }
  }
});

You only need to do two steps.

  1. Get the previousElementSibling of the button
  2. Add the className of "highlight" to that sibling
var list = document.getElementsByTagName('ul')[0];

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