Question

I am trying to test for an attribute in a dynamic php photo gallery that loads images from a folder into a gallery. The gallery uses lightbox to display the photo once clicked. This is what I’m using to test:

if( $('#lightboxImage').attr('src') !== 'undefined'){ do something here }

I’m getting an initial error (Cannot call method ‘attr’ of null) in debug I think because the #lightboxImage only has a ‘src’ attribute when an image from the gallery is clicked. Nothing is obviously clicked when the page first loads.

Any ideas on how to solve this?

Thanks

Answer 1

I’m with @Malvolio, your error doesn’t quite add up. You should not be getting the error you’re describing. To wit:

<img id="src" class="src" src="http://goo.gl/UohAz"><br/>
<img class="src" src=""><br/>
<img class="src">

console.log($('#nothing').attr('src'));
console.log($('#src').attr('src'));

http://jsfiddle.net/7ZGwe/

Running onload gives me:

undefined
http://goo.gl/UohAz

So your actual problem has to do with something else, as Malvolio suggests. I can’t necessarily speculate any better than what Malvolio has, except maybe jQuery() should be tried in place of $().

---

This is a little bit beside your underlying problem, but has to do with what you asked. Instead of doing a test, you could:

[src]:not([src=""])

http://jsfiddle.net/jSQ3P/3

In your selector and bypass the check. So in other words:

$('#lightboxImage[src]:not([src=""])').doStuff();