EDIT

/**

 * Attaches add more fields behaviour to any form.

 * Dynamic adding of fields requires:

 *   - a button to click to produce more fields (id="field-name-more")

 *   - a wrapper div around the set of fields to be duplicated (id="field-name-wrapper")

 *     additional fields will be prepended to the end of this fieldset

 *   - a hidden element counter with the current number of fields (id="field-name-count")

 *   - field-name should be replaced by a unique identifier for your field

 *   - a callback function which produces an additional field

 */

Drupal.linkAutoAttach = function() {

  $('input.more-email-addresses').each(function() {

    var uri = this.value;

    // Extract the base name from the id (my-text-field-url -> my-text-field).

    var base = this.id.substring(0, this.id.length - 9);

    var button = base + '-more';

    var wrapper = base + '-wrapper';

    var counter = base + '-count';

    var link = new Drupal.jslink(uri, button, wrapper, counter);

  });

  // set radioCheckbox group, assuming that jquery plugin for radiocheckboxes is loaded

  $.radioCheckboxGroup("", ".preferred-email");

}

/**

 * JS jslink object.

 */

Drupal.jslink = function(uri, button, wrapper, counter) {

  this.button = '#'+ button;

  this.wrapper = '#'+ wrapper;

  this.counter = '#'+ counter;

  Drupal.redirectFormButton(uri, $(this.button).get(0), this);

}

/**

 * Handler for the form redirection submission.

 */

Drupal.jslink.prototype.onsubmit = function() {

  // Increment count

  var count = parseInt($(this.counter).val());

  $(this.counter).val(count + 1);

}

/**

 * Handler for the form redirection completion.

 */

Drupal.jslink.prototype.oncomplete = function(data) {

  // Avoid unnecessary scrolling

  Drupal.freezeHeight();

  // Place HTML into temporary div

  var div = document.createElement('div');

  $(div).html(data);

  // Append to form and update behaviour

  $(div).hide();

  $(this.wrapper).append(div);

  $(div).slideDown('fast');

  Drupal.linkAutoAttach();

  Drupal.unfreezeHeight();

}

/**

 * Handler for the form redirection error.

 */

Drupal.jslink.prototype.onerror = function(error) {

  alert('An error occurred:\n\n'+ error);

}

// Global killswitch

if (Drupal.jsEnabled) {

  $(document).ready(Drupal.linkAutoAttach);

}