HTMLHelp Forums > How to get the number of elements with a non-empty class name

Full Version: How to get the number of elements with a non-empty class name

HTMLHelp Forums > Programming > Client-side Scripting

RainLover

May 25 2019, 03:36 AM

Sample code:

CODE

<!DOCTYPE html>
<html lang="en">

<head>
 <title>Get elements number</title>
</head>

<body>
 Hello, world!
 Hello, world!
 Hello, world!
 Hello, world!
 <script>
 console.log(document.querySelectorAll("p[class]").length);
 </script>
</body>

</html>

DEMO

What I get: 4
What I expect: 2

Christian J

May 25 2019, 06:19 AM

You might use the :not pseudoclass:

CODE

document.write(document.querySelectorAll("p:not([class=''])").length);

but note that the above will also match the following cases:

CODE

Hello, world!
Hello, world!

However this combination seems to work (newer browsers only, of course):

CODE

Hello, world!
Hello, world!
Hello, world!
Hello, world!
Hello, world!

<script>
document.write(document.querySelectorAll("p[class]:not([class='']):not([class=' '])").length); // "2"
</script>

You may still get a match for CLASS values consisting of two or more whitespaces though:

CODE

Hello, world!

You might strip all whitespace with the trim() method or regex, but then you probably can't use querySelectorAll:

CODE

Hello, world!
Hello, world!
Hello, world!
Hello, world!
Hello, world!

<script>
var p=document.getElementsByTagName('p');
var count=0;
for(var i=0; i<p.length; i++)
{
 p[i].className=p[i].className.trim();
 if(p[i].className!='')
 {
 count++;
 }
}
document.write(count); // "2"
</script>

RainLover

May 26 2019, 12:37 AM

QUOTE(Christian J @ May 25 2019, 06:19 AM)

You might use the :not pseudoclass:

CODE

document.write(document.querySelectorAll("p:not([class=''])").length);

Great! ❤
P.S. Isn't there any button on this forum to thank answerers, mark a post as helpful or choose it as the best answer?

Christian J

May 26 2019, 05:22 AM

You're welcome!

No, you must do it manually.

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