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 Getting a Handle on the DOM Select by Tag Name

Kennedy Malonga
Kennedy Malonga
22,856 Points
Posted by Kennedy Malonga
Kennedy Malonga
22,856 Points

Complete the code by setting the variable listItems to refer to an HTMLCollection. The collection should contain all lis

Cannot read property '1' of null

app.js 
// Complete the challenge by writing JavaScript below
const colors = ["#C2272D", "#F8931F", "#FFFF01", "#009245", "#0193D9", "#0C04ED", "#612F90"];
let listItems = document.getElementsByTagName("ul")[0];

for ( let i = 0; i < colors.length; i++ ) {
  listItems[i].style.color = colors[i];    
}
index.html 
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>JavaScript and the DOM</title>
  </head>
  <body>
    <h1>My List</h1>
    <ul>
      <li>This should be red</li>
      <li>This should be orange</li>
      <li>This should be yellow</li>
      <li>This should be green</li>
      <li>This should be blue</li>
      <li>This should be indigo</li>
      <li>This should be violet</li>
    </ul>
    <script src="app.js"></script>
  </body>
</html>

3 Answers

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

Looking at this line:

let listItems = document.getElementsByTagName("ul")[0];

This won't select a collection because the index ([0]) will limit the result to just the first element.
Also, the selector is targeting the unordered list itself (ul) and not the list items within it (li).

Gary M.
Gary M.
14,193 Points
Gary M.
Gary M.
14,193 Points

Use the following code:

let listItems = document.getElementsByTagName('li');

Michael MacKenzie
Michael MacKenzie
8,633 Points
Michael MacKenzie
Michael MacKenzie
8,633 Points

These answers are both incorrect. Please help with a proper answer and explanation? I have the same answer as Gary M. posted but I'm getting the same error as the original poster of this question.

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

Both answers are correct, though I was deliberately trying to help by explaining the issue without giving away the final answer. Coincidentally, I gave a very similar answer to someone with nearly the same issue just yesterday.

Gary just provided the answer without explanation (something generally frowned upon by the moderators).   :see_no_evil:
But you can copy Gary's line and paste it over line 3 of the challenge and it passes.