How to use the 'Only-of-Type' Pseudo-Class

The only-of-type pseudo-class is lesser-known but can be useful in CSS.

Let’s dive into a more detailed example to understand its functionality better.

What does it do?

The only-of-type pseudo-class in CSS is a selector that targets an element that is the only sibling of its type within its parent container. It’s like giving a special style to an element that’s the only one of its kind in a group.

For a clearer understanding, let’s consider a blog post scenario. We’ll have a section with a heading, some paragraphs, and images.

We will use only-of-type to style an image differently if it's the only image in the article. In this instance, we can highlight it in a green border if it's the only image in the article:

HTML Code:

  <h2>My Blog Post</h2>
  <p>Here's some introductory text about my blog post.</p>
  <img src="unique-image.jpg" alt="Unique Image">
  <p>More details about the topic discussed in the blog post.</p>
  <!-- Uncomment to see the change
  <img src="another-image.jpg" alt="Another Image">

CSS Code:

img:only-of-type {
  border: 3px solid green;
  display: block;
  margin: auto;

And so you can play with it, here's a CodePen with some slight variations so you can play with it:

In the HTML, the <article> element contains a mixture of <h2>, <p>, and <img> elements. The CSS targets any <img> element that’s the only one of its kind within its parent <article> and applies a green border.

So you'll notice in the CodePen that our second article on the page gets different styles because it's not the only image inside a tag.

Use cases for 'only-of-type'

This pseudo-class shines in scenarios where the presence or number of certain elements can vary. For instance, in a product listing, if there's only one featured product, you might want to highlight it differently than when there are several.

This pseudo-class is about recognizing and styling that one-of-a-kind element in a group!

Happy coding! ☘️

Avatar for Niall Maher

Written by Niall Maher

Founder of Codú - The web developer community! I've worked in nearly every corner of technology businesses; Lead Developer, Software Architect, Product Manager, CTO and now happily a Founder.


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