Sibling traversal objective

Question

I don't understand how to add a class of 'highlight' to a paragraph element? I assume this means to highlight the text? How does this work in javascript?

app.js

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

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

Answer 1 · 2017-07-10T19:25:04Z

July 10, 2017 7:25pm

This is checking if the event target is a button, and if it is, it is selecting the button's parent (the p) and adding a class to that element. The CSS would have rules that style anything with that class. So by adding the class name to the p element in JS, you are essentially pointing CSS rules to it. you could style those rules however you like in the CSS.

I like to use the classList.add(), classList.remove(), or classList.toggle() to be a little more current. Here is a great article that will cover those, and other DOM manipulation methods https://zellwk.com/blog/js-in-dom/

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Sibling traversal objective

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Jason Welsh

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