Behaviors not attaching in the 'before' operation

  after: function(data) {
    var object = $(data.data);
    $(data.selector).after(object);
    Drupal.attachBehaviors(object);
  },

but:

  before: function(data) {
    var html = $(data.selector).before(data.data);
    Drupal.attachBehaviors(html);
  },

The later cannot work.