Turns out jQuery has the handy has selector for just this case.

Here’s a simple example that sets the title attribute of every <a> tag that contains an <img> tag and then attaches Fancybox, a lightbox-esque, image-enlargement plugin:

$("a:has(img)").attr("title", "Click to enlarge").fancybox();

I liked this approach because it meant I didn’t have to remember to add a class (e.g. class="fancybox") to every <a> tag that linked to an image I wanted to enlarge. In fact, I didn’t have to do anything special at all. Brilliant!

And then I realized I had a problem. In a few instances on my blog, I used an image (like a Firefox or Ubuntu logo) to link to an external website. Even though a:has(img) was awesome in its expressive simplicity, it turned out to be a little overzealous in those instances.

What I really wanted was something slightly more specific: the ability to attach Fancybox to <a> tags that only linked to images. But how could I determine if I was linking to an image or not? How about by the file extension.

So I used the “attribute ends with” selector combined with the multiple selector to apply Fancybox to only those <a> tags that have href attributes that end with .jpg, .png, or .gif:

$("a[href$='.jpg'],a[href$='.png'],a[href$='.gif']").attr("title", "Click to enlarge").fancybox();

This had the added bonus of enabling Fancybox on the occasional bit of text I’d used to link directly to an image.