Many times we come to same problem which we faced so many times. But still when web developer comes in sitution of checking forms with simple javascript.
He started looking into some solutions. Some people try to use the some third party JS library like (Mootools, Jquery, lightbox, Prototype and etc…)
I recomend not to use these JS library because these library will take some brandwidth of your website. Most of the code these JS library is useless or un useful to your website.
Still you are adding these JS library to your website.