//ajax
function createRequestObject() {
    var tempXMLHttpObject;
    if (window.XMLHttpRequest) { // Mozilla, Safari
        tempXMLHttpObject = new XMLHttpRequest();
    } else if (window.ActiveXObject) { //IE
        tempXMLHttpObject = new ActiveXObject("Microsoft.XMLHTTP");
    }
    return tempXMLHttpObject;
}

//ajax
var http = createRequestObject();

//ajax
function makeGetRequest() {
    http.open('get', 'prices.php');
    http.onreadystatechange = processResponse;
    http.send(null);
}

//callback function
var renderFunction;

//ajax
function processResponse() {
    if (http.readyState == 4) {
        var response = http.responseText;

		var q = eval(response);
		
		var cl = q[0+1].current;
		var ho = q[1+1].current;
		var ng = q[2+1].current;
		var pn = q[3+1].current;
		
		//create an object to contain the prices
		var o = new Object();
		
		o.cl = cl;
		o.ho = ho;
		o.ng = ng;
		o.pn = pn;
		
		//return the object containing the prices
		renderFunction(o);

    }
}

//call this function from your html page
function updatePrices(rf) {
	//save a reference to the provided callback function
	renderFunction = rf;
	makeGetRequest();
}