var XMLHttpReq ;
function createXMLHttpRequest(){
	if(window.XMLHttpRequest){ //Mozilla 
		XMLHttpReq=new XMLHttpRequest();
			if (XMLHttpReq.overrideMimeType) {   
				XMLHttpReq.overrideMimeType("text/xml");   
			}  
	}
	else if(window.ActiveXObject){
		try{
			XMLHttpReq=new ActiveXObject("Msxml2.XMLHTTP");
		}catch(e){
			try{
				XMLHttpReq=new ActiveXObject("Microsoft.XMLHTTP");
			}catch(e){
			}
		}
	}
 
}
function sendajax(url,div,p){
	aa=div;
	pvar=p;
	
	
	createXMLHttpRequest();
	XMLHttpReq.open("GET",url,true);

	/*
	if(pvar=='option'){
		XMLHttpReq.onreadystatechange=getshops;
	}else{
		if(pvar=='D3'){
			XMLHttpReq.onreadystatechange=getcity;
		}else{
			XMLHttpReq.onreadystatechange=getinfo;
		}
		
	}
	*/
	switch (pvar)
	{
		case "option": XMLHttpReq.onreadystatechange=getshops;break;
		case "D3": XMLHttpReq.onreadystatechange=getcity;break;
		case "div": XMLHttpReq.onreadystatechange=getinfo;break;
		case "backcity": XMLHttpReq.onreadystatechange=backcity;break;
	
	}


	//alert(url);
	XMLHttpReq.setRequestHeader("If-Modified-Since","0");
	XMLHttpReq.send(null);
}

function getshops(){
	if(XMLHttpReq.readyState==4 &&XMLHttpReq.status==200){ 
		document.getElementById("D4").options.length=0;//清空原来的选项
		document.getElementById("D4").options.add(new Option("请选择商家",""));
		backvar=XMLHttpReq.responseText;
		arr=backvar.split('$$');
		//for (x in arr)
		for(x=0;x<arr.length-1;x++)
		{
			getv=arr[x].split('##');
			document.getElementById("D4").options.add(new Option(getv[1],getv[0]));
		}
		document.getElementById(aa).innerHTML= '';
	}
}

function getinfo(){
	if(XMLHttpReq.readyState==4 &&XMLHttpReq.status==200){ 
		document.getElementById(aa).innerHTML=unescape(XMLHttpReq.responseText);
	}else{
		document.getElementById(aa).innerHTML='<div style="text-align:center;><div style="text-align:center;width:500px"><br><br><img src="loading.gif"><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;正在更新数据...</div>';
	}
}

function getcity(){
	if(XMLHttpReq.readyState==4 &&XMLHttpReq.status==200){ 
		str=XMLHttpReq.responseText;
		arr=str.split('##');
		document.getElementById("D3").options.length=0;//清空原来的选项
		document.getElementById("D3").options.add(new Option("请选择城市"));
		for (i=0;i<=arr.length-2;i++){
			document.getElementById("D3").options.add(new Option(arr[i],arr[i]));

		}
	}
	
}


function backcity(){
	if(XMLHttpReq.readyState==4 &&XMLHttpReq.status==200){ 
		str=XMLHttpReq.responseText;
		arr=str.split('##');
		document.getElementById("city").options.length=0;//清空原来的选项
		document.getElementById("city").options.add(new Option("请选择城市"));
		for (i=0;i<=arr.length-2;i++){
			document.getElementById("city").options.add(new Option(arr[i],arr[i]));

		}
	}
	
}