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 Interactive Web Pages with JavaScript Traversing and Manipulating the DOM with JavaScript Traversing Elements

Sergio Cruz
Sergio Cruz
15,550 Points
Posted by Sergio Cruz
Sergio Cruz
15,550 Points

.querySelector("a") not working. I wrote listItems.querySelector("a"); but it doesnt go through

It shows an error that says: TypeError: 'undefined' is not a function. Evaluating: listItems.querySelector("a")

app.js 
//Select the naviagation
var navigation = document.getElementById("navigation");

//Select all listItems from the navigation
var listItems = navigation.children;

//When a navigation link is pressed
var linkListener = function() {
  console.log("Listener is clicked!");
}

var bindEventsToLinks = function(listItem) {
  //Select the anchor
  var anchor = listItems.querySelector("a");
  //Bind the linkListener to the anchor element (a) 
  anchor.onclick = linkListener;
}

for(var i = 0; i < listItems.length ; i++) {
    bindEventsToLinks(listItems[i]);
}
index.html 
<!DOCTYPE html>
<html>
<head></head>
<body>

<ul id="navigation">
  <li>
    <a href="#home">Home</a>
  </li>
  <li>
    <a href="#about">About</a>
  </li>
  <li>    
    <a href="#contact">Contact</a>
  </li>
</ul>

<p>A few of my favourite things:</p>
<ul>
  <li>
    Rain drops on roses
  </li>
  <li>
    Whiskers on kittens
  </li>
  <li>
    Brown paper packages wrapped up with string
  </li>
</ul>

<script src="app.js"></script>
</body>
</html>

3 Answers

Andrew Robinson
Andrew Robinson
16,372 Points
Andrew Robinson
Andrew Robinson
16,372 Points

Had to edit this answer, I assumed querySelector could only be used on a single node, turns out you are using 'listItem' not 'listItems' in your bindEventsToLinks function parameters.

Sascha Bratton
Sascha Bratton
3,671 Points
Sascha Bratton
Sascha Bratton
3,671 Points

Looks like you accidentally tried to run querySelector against the global listItems when you meant to run it against the listItem parameter in your bindEventsToLink function.

Sergio Cruz
Sergio Cruz
15,550 Points
Sergio Cruz
Sergio Cruz
15,550 Points

lol yeah it was just a typo. Thanks for helping!