Cross-Browser HTML5 Form Validation: jQuery.Html5form
jQuery.Html5form is a jQuery plugin that adds the lacking HTML5 form validation features to non-compatible browsers.
It doesn't require any custom functions or coding. Just create your form with the HTML5 syntax and it'll execute them automatically.
Optionally, the plugin offers features to help customizing how the errors will be handled like the the error messages, where they'll be displayed, their styles, etc.
And, it works with multiple forms on the same page as well (each of them can be customized differently).