:valid
The :valid selector allows you to select <input> elements that do not contain valid content, as determined by its type attribute. :valid is defined in the CSS Selectors Level 3 spec as a “validity pseudo-selector”, meaning it is used to style interactive elements based on an evaluation of user input.
This selector has one particular use: providing a user with feedback while they are interacting with a form on the page. The example below uses CSS to turn the “Email” fields red or green, responding to the whether or not the contents match a valid email address pattern:
Note how the first <input> (“Email”) is green—valid—even when there is no content in the field. This is because the input is optional, so leaving it blank would result in a valid form submission. To fix this behaviour, the second <input> has a “required” attribute, which means that a blank field would result in an invalid form submission.
Points of Interest
:validcan be “chained” with other pseudo-selectors: like:focusto only validate when the user is typing,:beforeor:afterto generate icons or text to provide more user feedback, or attribute selectors likeinput[value=""]to only validate input fields containing content.
Related Properties
Other Resources
Browser Support
| Chrome | Safari | Firefox | Opera | IE | Android | iOS |
|---|---|---|---|---|---|---|
| 10.0+ | 5.0+ | 4.0+ | 10.0+ | 10+ | Nope | Nope |
:valid was introduced in CSS Selectors Module 3, which means old versions of browsers do not support it. However, modern browser support is getting better. If you require older browser support, either polyfill, or use these selectors in non-critical ways á la progressive enhancement, which is recommended.
My attempt to explain the :valid selector: The :valid selector is basically a pseudo-class which can work together with the input element. Let’s say you use the input element to check if a user types something correct or wrong. Now with the :valid selector you can edit let’s say the color of an input field so the user knows if it is correct or wrong. If a word is typed correctly, the input box becomes green:
Browser compatibility: Chrome 10, Firefox 4, Internet explorer 10, Opera 10, Safari 5. Firefox mobile 4, Opera mobile 10, Safari 5. Here’s a very nice demo from the mozilla website: https://developer.mozilla.org/samples/cssref/input-validation.html
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