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 Java Script line for simple form validation.
It can prevent people from leaving fields blank, from entering too little or too much or from using invalid characters.
Normally you would modify this so that you could submit or not submit the form based on the number of items selected. For example, a text input that only needs to have a value if a checkbox is checked: Using simple logical operators and the functions supplied above you can do all sorts of client-side form validation.