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JavaScript JavaScript and the DOM (Retiring) Responding to User Interaction Event Delegation

Kimberly Dolcin
Kimberly Dolcin
4,369 Points
Posted by Kimberly Dolcin
Kimberly Dolcin
4,369 Points

what is wrong with my conditional statement?

e

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];
if (e.target.tagName === "INPUT") {
section.addEventListener('click', (e) => {
  e.target.style.backgroundColor = 'rgb(255, 255, 0)';
});}
Matthew Lanin
seal-mask
.a{fill-rule:evenodd;}techdegree
Matthew Lanin
Full Stack JavaScript Techdegree Student 8,003 Points
Matthew Lanin
.a{fill-rule:evenodd;}techdegree
Matthew Lanin
Full Stack JavaScript Techdegree Student 8,003 Points

Is the app.js code snippet you provided within another event listener? If not, I believe the "e" within the conditional wouldn't yet be defined, since there isn't yet an event object that it is referencing. If it is, would you mind posting the rest of your app.js code?

EDIT:

Yeah, so your conditional is right, you just put it in the wrong place. You want to add the event listener, and then apply the backgroundColor only IF the conditions are met. Right now, you are asking if a condition is met, and then adding the event listener, and then trying to apply the backgroundColor property. Problem is, the "e" in the conditional isn't defined until there is an event to reference.

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

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

Edit: removed extra curly brace caught by Elijah, good catch!

Elijah Quesada
.a{fill-rule:evenodd;}techdegree seal-36
Elijah Quesada
Front End Web Development Techdegree Graduate 32,965 Points

Matt - codes looks great, however you have an extra curly brace on line 7 that will cause an error.

1 Answer

Elijah Quesada
.a{fill-rule:evenodd;}techdegree seal-36
Elijah Quesada
Front End Web Development Techdegree Graduate 32,965 Points

Your if statement needs to be inside of the addEventListener. 

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

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