:valid, :invalid, and :required CSS Pseudo Classes
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!
![Designing for Simplicity]()
Before we get started, it's worth me spending a brief moment introducing myself to you. My name is Mark (or @integralist if Twitter happens to be your communication tool of choice) and I currently work for BBC News in London England as a principal engineer/tech...
![CSS @supports]()
Feature detection via JavaScript is a client side best practice and for all the right reasons, but unfortunately that same functionality hasn't been available within CSS. What we end up doing is repeating the same properties multiple times with each browser prefix. Yuck. Another thing we...
![Element Position Swapping Using MooTools 1.2]()
We all know that MooTools 1.2 can do some pretty awesome animations. What if we want to quickly make two element swap positions without a lot of fuss? Now you can by implementing a MooTools swap() method.
MooTools 1.2 Implementation
MooTools 1.2 Usage
To call the swap...
![Flexbox Equal Height Columns]()
Flexbox was supposed to be the pot of gold at the long, long rainbow of insufficient CSS layout techniques. And the only disappointment I've experienced with flexbox is that browser vendors took so long to implement it. I can't also claim to have pushed flexbox's limits, but...
A small note:
:beforeand:afteronly works with elements that have content.inputs doesn’t, so these pseudo-elements won’t work.Amazing post, so in your example you are testing it with input text and email address is that all ?!
“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?
@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.
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
Bug in IE usign pseudo-elements
http://codepen.io/diegoleme/pen/cJyjF
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