cocoon/app/assets/javascripts/cocoon.js

(function($) {

  var cocoon_element_counter = 0;

  function replace_in_content(content, regexp_str, with_str) {
    reg_exp = new RegExp(regexp_str);
    content.replace(reg_exp, with_str);
  }

  function trigger_before_removal_callback(node) {
    node.trigger('cocoon:before-remove');
  }

  function trigger_after_removal_callback(node) {
    node.trigger('cocoon:after-remove');
  }

  $('.add_fields').live('click', function(e) {
    e.preventDefault();
    var $this                 = $(this),
        assoc                 = $this.data('association'),
        assocs                = $this.data('associations'),
        content               = $this.data('association-insertion-template'),
        insertionMethod       = $this.data('association-insertion-method') || $this.data('association-insertion-position') || 'before';
        insertionNode         = $this.data('association-insertion-node'),
        insertionTraversal    = $this.data('association-insertion-traversal'),
        regexp_braced         = new RegExp('\\[new_' + assoc + '\\](.*?\\s)', 'g'),
        regexp_underscord     = new RegExp('_new_' + assoc + '_(\\w*)', 'g'),
        new_id                = new Date().getTime() + cocoon_element_counter++,
        newcontent_braced     = '[' + new_id + ']',
        newcontent_underscord = '_' + new_id + '_',
        new_content           = content.replace(regexp_braced, '[' + new_id + ']$1');

    if (new_content == content) {
        regexp_braced     = new RegExp('\\[new_' + assocs + '\\](.*?\\s)', 'g');
        regexp_underscord = new RegExp('_new_' + assocs + '_(\\w*)', 'g');
        new_content       = content.replace(regexp_braced, '[' + new_id + ']$1');
    }

    new_content = new_content.replace(regexp_underscord, newcontent_underscord + "$1");

    if (insertionNode){
      if (insertionTraversal){
        insertionNode = $this[insertionTraversal](insertionNode)
      } else {
        insertionNode = insertionNode == "this" ? $this : $(insertionNode);
      }
    } else {
      insertionNode = $this.parent();
    }

    var contentNode = $(new_content);

    insertionNode.trigger('cocoon:before-insert');

    // allow any of the jquery dom manipulation methods (after, before, append, prepend, etc)
    // to be called on the node.  allows the insertion node to be the parent of the inserted
    // code and doesn't force it to be a sibling like after/before does. default: 'before'
    insertionNode[insertionMethod](contentNode);

    insertionNode.trigger('cocoon:after-insert');
  });

  $('.remove_fields.dynamic').live('click', function(e) {
    var $this = $(this);
    var trigger_node = $this.closest(".nested-fields").parent();
    trigger_before_removal_callback(trigger_node);
    e.preventDefault();
    $this.closest(".nested-fields").remove();
    trigger_after_removal_callback(trigger_node);
  });

  $('.remove_fields.existing').live('click', function(e) {
    var $this = $(this);
    var trigger_node = $this.closest(".nested-fields").parent();
    trigger_before_removal_callback(trigger_node);
    e.preventDefault();
    $this.prev("input[type=hidden]").val("1");
    $this.closest(".nested-fields").hide();
    trigger_after_removal_callback(trigger_node);
  });

})(jQuery);