var rcXmlHttp;

function rcGetXmlHttpObject() {
	var xmlHttp = null;

	// Firefox, Opera 8.0+, Safari
	try {
		xmlHttp = new XMLHttpRequest();

	// Internet Explorer
	} catch(e) {
		try {
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch(e) {
			xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		}
	}

	return xmlHttp;
}

function rcChange(wpurl, args, start) {

	// 得到 XMLHTTP 对象. 如果找不到, 报出 Message 并不进行任何操作.
	rcXmlHttp = rcGetXmlHttpObject();
	if (rcXmlHttp == null) {
		alert ("Oop! Browser does not support HTTP Request.")
		return;
	}

	var url = wpurl;
	url += "?action=rc_ajax";
	url += "&args=" + args;
	url += "&start=" + start;

	rcXmlHttp.onreadystatechange = runRcChange;
	rcXmlHttp.open("GET", url, true);
	rcXmlHttp.send(null);
}

function runRcChange() {
	var parent = document.getElementById('rc_nav').parentNode;

	if (rcXmlHttp.readyState == 4 || rcXmlHttp.readyState=="complete") {
		parent.innerHTML = rcXmlHttp.responseText;
	}
}