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JavaScript JavaScript and the DOM (Retiring) Getting a Handle on the DOM Practice Selecting Elements

Posted by Jun Hong Lin
Jun Hong Lin
4,641 Points

How to use "Descendant Selector" correctly in this challenge task?

I've referenced the MDN doc and animate the way they write , however, my selector cannot select all right <li> inside <nav><ul></ul></nav>.

(https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelectorAll#javascript)

js/app.js 
const select = document.querySelector('nav');
let navigationLinks = select.querySelectorAll('li');
let galleryLinks;
let footerImages;
index.html 
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Nick Pettit | Designer</title>
    <link rel="stylesheet" href="css/normalize.css">
    <link href='http://fonts.googleapis.com/css?family=Changa+One|Open+Sans:400italic,700italic,400,700,800' rel='stylesheet' type='text/css'>
    <link rel="stylesheet" href="css/main.css">
    <link rel="stylesheet" href="css/responsive.css">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
  </head>
  <body>
    <header>
      <a href="index.html" id="logo">
        <h1>Nick Pettit</h1>
        <h2>Designer</h2>
      </a>
      <nav>
        <ul>
          <li><a href="index.html" class="selected">Portfolio</a></li>
          <li><a href="about.html">About</a></li>
          <li><a href="contact.html">Contact</a></li>
        </ul>
      </nav>
    </header>
    <div id="wrapper">
      <section>
        <ul id="gallery">
          <li>
            <a href="img/numbers-01.jpg">
              <img src="img/numbers-01.jpg" alt="">
              <p>Experimentation with color and texture.</p>
            </a>
          </li>
          <li>
            <a href="img/numbers-02.jpg">
              <img src="img/numbers-02.jpg" alt="">
              <p>Playing with blending modes in Photoshop.</p>
            </a>
          </li>
        </ul>
      </section>
      <footer>
        <a href="http://twitter.com/nickrp"><img src="img/twitter-wrap.png" alt="Twitter Logo" class="social-icon"></a>
        <a href="http://facebook.com/nickpettit"><img src="img/facebook-wrap.png" alt="Facebook Logo" class="social-icon"></a>
        <p>&copy; 2016 Nick Pettit.</p>
      </footer>
    </div>
  <script src="js/app.js"></script>
  </body>
</html>

6 Answers

Peter Vann
Peter Vann
36,427 Points

Hi Jun!

No - with querySelectorAll('nav a'), you are targeting ALL anchor tags nested within the nav element, regardless of how deeply nested within (other elements also nested within) the nav element they may be.

Which is cool and convenient, in my book!?!

More info:

https://www.w3schools.com/css/css_combinators.asp

(Try running some experiments there - I do all the time.)

I hope that helps.

Stay safe and happy coding!

Peter Vann
Peter Vann
36,427 Points
Peter Vann
Peter Vann
36,427 Points

Hi Jun!

A descendant selector is merely one CSS selector, a space, and then another CSS selector - the first one being the parent element, the second being the nested children selectors.

This passes all three tasks:

let navigationLinks = document.querySelectorAll('nav a'); // Task 1
let galleryLinks = document.querySelectorAll('#gallery a'); // Task 2
let footerImages = document.querySelectorAll('footer img'); // Task 3

Note: You need to use document.querySelectorAll() since you are target ALL the child links, not just 1.

I hope that helps.

Stay safe and happy coding!

Jun Hong Lin
Jun Hong Lin
4,641 Points
Jun Hong Lin
Jun Hong Lin
4,641 Points

Thanks for your help!

Now, I've learned it would be better to select precisely or directly nested children element <a>, instead of just select <li>.

I'm still little bit confused, isn't it necessary to select step by step like nav -> ul -> -> li -> a?

Jun Hong Lin
Jun Hong Lin
4,641 Points
Jun Hong Lin
Jun Hong Lin
4,641 Points

Thanks a lot!

mafk Goose
mafk Goose
170 Points
mafk Goose
mafk Goose
170 Points

At which point did we learn about selecting all anchor tags nested within a parent node. The 'a' really threw me off there? I don't recall learning about this..

mafk Goose
mafk Goose
170 Points

I retract my question, however I don't recall learning how to select particular nested elements within the dom. Makes enough sense though.

Peter Vann
Peter Vann
36,427 Points
Peter Vann
Peter Vann
36,427 Points

Hi Mafk!

Yea, a is an anchor/link tag.

And also, again, a descendant selector is merely one CSS selector, a space, and then another CSS selector - the first one being the parent element, the second being the nested children selectors.

And one cool thing, the descendant selector will target ANY targeted children, no matter deeply nested (within other child tags).

I hope that helps.

Stay safe and happy coding!