To take things a step further you can even explore Ajax Form Validation which lets you supply real-time feedback using server-side scripts triggered by Java Script events.
The team at have made a video based on this article as a part of their Java Script training lessons which you can view below. Would be great if you could post full examples of code including form and not just pieces that fit into the greater framework of code.
It explains some of the code examples above as well as introducing more advanced concepts: We would be remiss in not pointing out that your Java Script and HTML code should be kept separated as far as possible. I've coded a working form, all checks are great but for some reason the hardest part is trying to stop form submission before validation.
So i have places to insert the stop validation code, but just cant find any that works.
If you're working with arrays of checkboxes to submit data to a server-side script then you might already have some grey hairs from trying to figure out how to validate the input using Java Script.
But if the user unchecks the box, the user DOESNT have to enter info in textarea.
Most modern browsers now support HTML5 Form Validation making it possible to validate form elements without (or before) any Java Script is triggered.
The value of a text input box (or a textarea or password input) is available using the syntax that tells you which option has been selected.
This is done using HTML5 form validation techniques and CSS, but it only validates the input format (pattern) and not the actual values.