Autocomplete with Prototype

if($("plane_airport_id")) {
		new Form.Element.Observer('plane_airport_id', 0.1, function(event) {
			var string = $F('plane_airport_id');
			if (string.length >= 3) {
				new Ajax.Request('/airports', {method:'get',parameters:{search:string},
					onSuccess: function(transport) {
						var airports = transport.responseJSON;
						var lis = $('airport-list').descendants();
						if (lis.length > 0) {
							lis.each(function(l) {
								l.remove();
							});
						};
						airports.each(function(a) {
							var item = "<li class='airport'><a href='javascript:;' class='airport-link'>" + a + "</a></li>";
							$('airport-list').insert(item);
						});
						$$('.airport-link').each(function(a) {
							a.observe("click", function() {
								var text = $(this).innerHTML;
								Form.Element.setValue('plane_airport_id',text);
							});
						});
					}
				});
			} else {
				var lis = $('airport-list').descendants();
				if (lis.length > 0) {
					lis.each(function(l) {
						l.remove();
					});
				};
			};
		});
	};