:valid, :invalid, and :required CSS Pseudo Classes

By  on  

Let's be honest, form validation with JavaScript can be a real bitch.  On a real basic level, however, it's not that bad.  HTML5 has jumped in to some extent, providing a few attributes to allow us to mark fields as required or only valid if matching a given regular expression.  What some people don't know is that you can style elements base on their required, valid, or invalid values.  Here's how!

The CSS

Each state is colon-separated from the element it's associated with:

/* basics */
input:required {
	border: 1px solid blue;
}
input:valid {
	border: 1px solid green;
}
input:invalid {
	border: 1px solid red;
}

These pseudo classes are straight forward and useful. Here we're changing only borders, but you could use :before and :after to place text or an image next to each field, representing their state.

Being able to style elements based on invalid or valid information is something we've shimmed forever with JavaScript, but now we can do so (to some degree) with pure CSS!

Recent Features

  • By
    Write Better JavaScript with Promises

    You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...

  • By
    CSS Animations Between Media Queries

    CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...

Incredible Demos

  • By
    Face Detection with jQuery

    I've always been intrigued by recognition software because I cannot imagine the logic that goes into all of the algorithms. Whether it's voice, face, or other types of detection, people look and sound so different, pictures are shot differently, and from different angles, I...

  • By
    Create GitHub-Style Buttons with CSS and jQuery, MooTools, or Dojo JavaScript

    I'm what you would consider a bit of a GitHub fanboy. We all know that GitHub is the perfect place to store repositories of open source code, but I think my love of GitHub goes beyond that. GitHub seems to understand that most...

Discussion

  1. A small note: :before and :after only works with elements that have content. inputs doesn’t, so these pseudo-elements won’t work.

  2. Amazing post, so in your example you are testing it with input text and email address is that all ?!

  3. “now we can do so (to some degree) with pure CSS!”

    could you please go into more detail about that degree? Browser support? Is this CSS3 only?

  4. @Sumit – I can’t find any references on caniuse.com or anything similar. From my testing it works on: latest Chrome, latest Firefox, lateset Safari and IE10+. It doesn’t work on IE9 or below.

  5. The :before and :after pseudo-elements elements interact with other boxes… as if they were real elements inserted just inside their associated element. More… http://www.corelangs.com/css/basics/pseudo.html CSS pseudo-elements

    Eric

  6. Diego Leme

    Bug in IE usign pseudo-elements
    http://codepen.io/diegoleme/pen/cJyjF

  7. A pseudo-class is similar to a class in HTML, but it’s not specified explicitly in the markup. Some pseudo-classes are dynamic — they’re applied as a result of user interaction with the document.
    for full implementation of pseudo class to refer here:
    http://www.mindstick.com/blog/711/CSS%20Pseudo%20Class

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!