var d = document; 
var div_select; 
var req = Create();  

function Country() 
{ 
div_select = "city";     
d.getElementById('city').innerHTML = ''; 
var a = d.getElementById('country_id').value; 
query = "country_id="+a; 
Request(query); 
} 

//var iID = window.setInterval(Country, 1000);

function Create() {
	if (navigator.appName == "Microsoft Internet Explorer") {
		req = new ActiveXObject("Microsoft.XMLHTTP");
	} else {
		req = new XMLHttpRequest();
	}
	return req;
}

function Request(query) 
{ 
req.open('post', 'http://www.clientbase.ru/selects.php' , true ); 
req.onreadystatechange = Refresh; 
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=utf-8"); 
req.send(query);              
}  
function Refresh() 
{ 
var a,b;
a = req.readyState; 
	if( a == 4 ) 
	{
	b = req.responseText;  
    
    d.getElementById(div_select).innerHTML = b; 
	}
}