gistfile1.js

$('#my_form').submit(function(event) {
  $.ajax({
    type: 'POST',
    dataType: 'json',
    data: $(event.target).serialize(),
    url: event.target.action,
    success: function(json) {
      if (json['success'] == true) {
        window.location = json['redirect_to'];
      } else {
        $('#form_errors').html(json['errors']);
      }
    },
    error: function(request, error) {
      alert(error);
    }
  });
  return false;
});