function createRequestObject() {
    var ro;
    var browser = navigator.appName;
    if(browser == "Microsoft Internet Explorer"){
        ro = new ActiveXObject("Microsoft.XMLHTTP");
    }else{
        ro = new XMLHttpRequest();
    }
    return ro;
}

var http = createRequestObject();

function getRates()
{

	var data = document.forms.booking.rates.value;
	var date = document.forms.booking.save_date.value;

	var url = "_ajax.php";
	var data = "data=" + data + "&date=" + date;
	
	//document.write(data);

	http.open("POST", url, true);
	http.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    http.send(data);
	http.onreadystatechange = returnRates;

}

function returnRates() {
  if (http.readyState == 4) {
    if (http.responseText.indexOf('invalid') == -1) {
      qresults = http.responseText.split("+");
		document.forms.booking.adult_rate.value = qresults[0];
		document.getElementById('adult_description').innerHTML = '£' + qresults[0] + ' per adult';
		document.forms.booking.child_rate.value = qresults[1];
		document.getElementById('child_description').innerHTML = '£' + qresults[1] + ' per child';
    }
  }
}