var xmlHttp;

function createXMLHttpRequest()
{
	if (window.ActiveXObject)
	{
		xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
	}
	else if (window.XMLHttpRequest)
	{
		xmlHttp = new XMLHttpRequest();
	}
}

function getCityList()
{
	var county = document.getElementById("county").value;
	var url = "/ajax/get_city_list.php?county=" + county;
	if (xmlHttp == undefined)
	{
		createXMLHttpRequest();
	}
	
	xmlHttp.open("GET", url);
	xmlHttp.onreadystatechange = updateCityList;
	xmlHttp.send(null);
}

function updateCityList()
{
	if (xmlHttp.readyState == 4)
	{
		if (xmlHttp.status == 200)
		{
			var cities = xmlHttp.responseText.split("|");
			var counter = 0;
			
			document.getElementById("city").options.length = 0;
			document.getElementById("city").options[0] = new Option("","");
						
			while (counter < cities.length)
			{
				document.getElementById("city").options[counter+1] = new Option(cities[counter], cities[counter]);
				counter += 1;
			}
		}
	}
}