var xmlHttp

function GetXmlHttpObject()
{ 
	var objXMLHttp=null
	if (window.XMLHttpRequest)
	{
		objXMLHttp=new XMLHttpRequest()
	}
	else if (window.ActiveXObject)
	{
		objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
	}
	return objXMLHttp
}


//============== Model ================
function show_cost(start,tripid)
{ 
 if(start!=""){
	xmlHttp=GetXmlHttpObject()
	if (xmlHttp==null)
	{
		alert ("Browser does not support HTTP Request")
		return
	} 
	var url="getacost.php"
	url=url+"?start="+start+"&tripid="+tripid
	url=url+"&sid="+Math.random()
	xmlHttp.onreadystatechange=onchange
	xmlHttp.open("GET",url,true)
	xmlHttp.send(null)
	
 }
}

function onchange() 
{ 
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
	{ 
	document.getElementById("display_cost").innerHTML=xmlHttp.responseText 
	} 
	
}