Edit in JSFiddle

;(function($) {

   var $user = $('#usuario');

   if( _userdata.session_logged_in !== 1 ) {
      $user.remove();
   }
   else {
      $user.find('.username').text( _userdata.username );
      $user.find('.avatar').html( 'src', _userdata.avatar );
   }

} (jQuery));