function $(id)
{
	return document.getElementById(id);	
}
function echo(obj,html)
{
	$(obj).innerHTML=html;
}
function createxmlhttp()
{
	var xmlhttp = false;
	try	
	{
  		xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
 	} 
	catch (e) 
	{
  		try 
  		{
   			xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
  		} 
		catch (e) 
		{
   			xmlhttp = false;
 		}
 	}
	if (!xmlhttp && typeof XMLHttpRequest!='undefined') 
	{
  		xmlhttp = new XMLHttpRequest();
		if (xmlhttp.overrideMimeType)
		{
			//设置MiME类别 
			xmlhttp.overrideMimeType('text/xml');
		}
	}
	return xmlhttp;	
}
//向服务器获取数据
function changeChild(id,tab)
{
        
        var tabs = tab.parentNode.parentNode.getElementsByTagName('span');
		for (var i = 0; i < tabs.length; i++) {
			tabs[i].className = (tab == tabs[i]) ? 'navcurr' : 'nav2';
		}
		
        var url="/getChild.aspx?id="+id;
		var xmlhttp= createxmlhttp();
		xmlhttp.onreadystatechange=requestdata;
		xmlhttp.open("POST", url, true);
		xmlhttp.setRequestHeader("If-Modified-Since","0");
		xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
		xmlhttp.send(null);
		function requestdata()
		{
			if(xmlhttp.readyState==4)
			{
				if(xmlhttp.status==200)
				{
					document.getElementById("td1").innerHTML = xmlhttp.responseText; 
				}
			}
		}
	  
		
}