Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Posted by Gary Sellergren
Gary Sellergren
1,448 Points

getElementsByTagName - How does it work with nested tags?

Why is nav not an element? it seems it would be based on this example from MDN: var div1Paras = div1.getElementsByTagName('p');

js/app.js 
let navigationLinks = nav.getElementsByTagName('a');
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>

1 Answer

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi there! Yes I found the MDN documentation you're referring to here. But you're neglecting the line before it. Let's take a look at both lines:

// this line selects the div with the id "div1" and assigns it to the variable div1
  var div1 = document.getElementById("div1")

//  this line selects the paragraphs from within the element stored
// in the div1 variable and assigns it to div1Paras
  var div1Paras = div1.getElementsByTagName("p");

The word nav as you have it is not a predefined word within JavaScript as document is. So we first would have to set up a variable to hold the nav element. Remember, that if you use getElementsByTagName it's going to return a collection of elements (even if there's only 1). These will be accessed using subscripting just like an array.

Once you've assigned that to a variable you can then retrieve all the anchor tags stored inside the variable holding the navigation element.

I'll get you started:

// this will store the nav element
myNav = document.getElementsByTagName('nav')[0];

Now, I'll leave it to you to get all the anchor elements inside of myNav and store them in navigationLinks.

Also, there is a much shorter way to do this but it requires the use of querySelectorAll() in conjunction with previous knowledge about CSS selectors. If you do not know CSS yet, this will not be obvious.

Hope this helps! :sparkles: