Parsley

Parsley, the ultimate JavaScript form validation library. Validating forms frontend have never been so powerful and easy. Like no other form validation library, simply write in English your requirements inside your form HTML tags, Parsley will do the rest! No need to write even a single JavaScript line for simple form validation. Parsley is now smarter, it automatically detects your forms' modifications and adapts its validation accordingly. Simply add, remove or edit fields, Parsley validation will follow! Parsley is shipped with more than a dozen useful validators. If not enough, use the awesome Parsley extra Ajax validator or tons of other extended validators provided by the community. Parsley strongly focuses on #UI and #UX. Override almost every Parsley default behavior to fit your exact needs. Still ships almost bug free. Parsley is strongly tested, and aims to work on every browser (including IE8).