var url = "GetPriceData.php?id="; // The server-side script

function handleHttpResponse() 
{   
	if (http.readyState == 4) 
	{
    	if(http.status==200) 
		{
			var results=http.responseText;
			document.getElementById('default_price').innerHTML = "$" + results;
		}
    }
}
       
function requestPriceInfo() 
{
	var sId = document.getElementById("category_id").value;
	http.open("GET", url + escape(sId), true);
	http.onreadystatechange = handleHttpResponse;
	http.send(null);
}

function getHTTPObject() 
{
	var xmlhttp;

	if(window.XMLHttpRequest)
	{
		xmlhttp = new XMLHttpRequest();
	}
	else if (window.ActiveXObject)
	{
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		if (!xmlhttp)
		{
		xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
		}  
	}

	return xmlhttp;
}

var http = getHTTPObject(); // We create the HTTP Object