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

Posted by Mohamed Boussaid
Mohamed Boussaid
2,534 Points

Filtering out all but the 'INPUT' elements not working with RETURN

Hi,

See description. Please help.

Thx,

Mohamed

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

section.addEventListener('click', (e) => {
    if(e.target.tagName == 'LI') {
    return; // intention: do nothing
    }
    else 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>

3 Answers

Steven Parker
Steven Parker
231,008 Points
Steven Parker
Steven Parker
231,008 Points

As you said, you need to filter out all but the 'INPUT' elements, but right now only 'LI" elements are being filtered and other elements in the section (besides the inputs) are still being affected.

Mohamed Boussaid
Mohamed Boussaid
2,534 Points

Hi Steven,

I tried e.target.tagName == 'input' as well. But did not work :s

Steven Parker
Steven Parker
231,008 Points
Steven Parker
Steven Parker
231,008 Points

But you want to filter out everything BUT the inputs, so:

    if (e.target.tagName != 'INPUT') {

And you don't need "else" when the "if" performs a "return".

Steven Parker
Steven Parker
231,008 Points
Steven Parker
Steven Parker
231,008 Points

That loop gets the job done, but it doesn't actually fulfill the challenge. The challenge asks you to "Add a condition ..." but there's no condition in the loop solution. You were very close both times but you switched approaches which changed the needs of the condition.

So if you were to apply the suggestions I made the first time you would have this valid (but unconventional) solution using "return":

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

section.addEventListener('click', (e) => {
  if (e.target.tagName != 'INPUT') return;              // do nothing if not an input
  e.target.style.backgroundColor = 'rgb(255, 255, 0)';
});

The second suggestion would have yielded the more common valid solution:

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

section.addEventListener('click', (e) => {
  if (e.target.tagName == 'INPUT')                      // change ONLY an input
    e.target.style.backgroundColor = 'rgb(255, 255, 0)';
});

I hope this has helped. You can mark a question solved by choosing a "best answer".
And happy coding!

Mohamed Boussaid
Mohamed Boussaid
2,534 Points
Mohamed Boussaid
Mohamed Boussaid
2,534 Points

Still not working. See below. 

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

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

});

Other question: Is there an explanation for tagName to be in capital letters?

Steven Parker
Steven Parker
231,008 Points
Steven Parker
Steven Parker
231,008 Points

This code is isn't using the "return" any more. Now you do need an equal (==) instead of not equals (!=).

And the tagName property is always in upper case, as per the HTML specifications.

Mohamed Boussaid
Mohamed Boussaid
2,534 Points
Mohamed Boussaid
Mohamed Boussaid
2,534 Points

I'm back again. Good news: understand and solved challenge :) My solution:

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

section.addEventListener('click', () => {

  for(let i=0; i<input.length; i++) { 
  input[i].style.backgroundColor = 'rgb(255, 255, 0)';
  }
});

Bad news: Do not know how to solve with e.target.Tagname. Feel free to post your answer. I'm curious to know better :)

Steven Parker
Steven Parker
231,008 Points
Steven Parker
Steven Parker
231,008 Points

See the comments i added to my answer.