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) Responding to User Interaction Event Delegation

Tauan Flores
seal-mask
.a{fill-rule:evenodd;}techdegree
Tauan Flores
Front End Web Development Techdegree Student 5,277 Points
Posted by Tauan Flores
.a{fill-rule:evenodd;}techdegree
Tauan Flores
Front End Web Development Techdegree Student 5,277 Points

Why is the first example incorrect, while the other works. Selecting only child elements in a eventlistener.

let section = document.getElementsByTagName('section')[0];

section.addEventListener('click', (e) => { if(event.target.tagName == "li") { e.target.style.backgroundColor = 'rgb(255, 255, 0)'; } });

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>JavaScript is an exciting language that you can use to power web servers, create desktop programs, and even control robots. But JavaScript got its start in the browser way back in 1995.</p>
            <hr>
            <p>Things to Learn</p>
            <ul>
                <li>Item One: <input type="text"></li>
                <li>Item Two: <input type="text"></li>
                <li>Item Three: <input type="text"></li>
                <li>Item Four: <input type="text"></li>
            </ul>
            <button>Save</button>
        </section>
        <script src="app.js"></script>
    </body>
</html>
app.js 
let section = document.getElementsByTagName('section')[0];

section.addEventListener('click', (div) => { 
  if(div.target.tagName == 'INPUT') { 
    div.target.style.backgroundColor = 'rgb(255, 255, 0)'; 
  } 
});

1 Answer

Andrew Hickman
seal-mask
.a{fill-rule:evenodd;}techdegree
Andrew Hickman
Full Stack JavaScript Techdegree Student 10,013 Points
Andrew Hickman
.a{fill-rule:evenodd;}techdegree
Andrew Hickman
Full Stack JavaScript Techdegree Student 10,013 Points

Hey there Tauan! Great question. The reason your first snippet doesn't work is because you are targeting the click event on the LI element. You'll find if you click on the text next to the input field, it turns yellow as expected. If you'd like the input field to turn yellow, target the tag name "input". Please note that I also changed the conditional in the callback function from "event" to the plain "e" you defined in the parameter for your event listener.

let section = document.getElementsByTagName('section')[0];

section.addEventListener('click', (e) => { 
    if(e.target.tagName == "input") { 
    e.target.style.backgroundColor = 'rgb(255, 255, 0)';
   } 
});