: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!
![Create a CSS Cube]()
CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals. Add animation and you've got something really neat. Unfortunately each CSS cube tutorial I've read is a bit...
![Create a Sheen Logo Effect with CSS]()
I was inspired when I first saw Addy Osmani's original ShineTime blog post. The hover sheen effect is simple but awesome. When I started my blog redesign, I really wanted to use a sheen effect with my logo. Using two HTML elements and...
![pointer Media Query]()
As more devices emerge and differences in device interaction are implemented, the more important good CSS code will become. In order to write good CSS, we need some indicator about device capabilities. We've used CSS media queries thus far, with checks for max-width and pixel ratios.
![Reverse Element Order with CSS Flexbox]()
CSS is becoming more and more powerful these days, almost to the point where the order of HTML elements output to the page no longer matters from a display standpoint -- CSS lets you do so much that almost any layout, large or small, is possible. Semantics...
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