recursive func for dropdown (js)

gistfile1.js

  
  var folders = <?=$json_encode($folders)?>,
      indent = [],
      
  get_menu = function(folders, folder_id){
		var html = '';
		if(typeof folder_id == 'undefined')
			folder_id = 0;
		folders.forEach( function(folder) {
			if(folder.file_parent_id == folder_id) {
				if(folder.file_parent_id > 0)
					indent[folder.id] = indent[folder.file_parent_id]+1;
				else
					indent[folder.id] = 0;
				html += '<option value="'+folder.id+'">';
				for(var i = 0; i < indent[folder.id]; i++)
				{
					html += '---';
				}
				html += folder.file_display_name+'</option>';
				html += get_menu(folders, folder.id);
			}
		});
	  return html;
	};
	
	$('select#menu').html(get_menu(folders));