Add jQuery form validation where HTML5 validation is not supported (Safari)

validation.js

  $("form").submit(function(e) {

    var ref = $(this).find("[required]");

    $(ref).each(function() {
        if ( $(this).val() == '' ) {
            alert("Required field should not be blank.");
            $(this).focus();
            e.preventDefault();
            return false;
        }
    });  return true;
  });