var xmlHttp;

function createXMLHttpRequest() {
    if (window.ActiveXObject) {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    } else if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();
    }
}

function startRequest(resource, params, callback_fun_name) {
    createXMLHttpRequest();
    eval("xmlHttp.onreadystatechange = " + callback_fun_name + ";");
    xmlHttp.open("GET", resource + "?" + params + "&t=" + new Date().getTime(), true);
    xmlHttp.send(null);
}


function userCheckname()
{
	var obj = document.getElementById('txtUserName_msg');
	if (xmlHttp.readyState == 4) 
	{
		if (xmlHttp.status == 200)
		{
			var data = xmlHttp.responseText;
			if (data == "false") 
			{
				showError(obj, "对不起！此帐号已被人注册!请您另选帐号")
				checkUserName=false;
				inputUserName=document.getElementById('txtUserName').value.trim();
				return false;
			} 
			if (data == "true")
			{
				showRight(obj,"恭喜您！此帐号现无人使用!请继续注册。")
				checkUserName=true;
				inputUserName=document.getElementById('txtUserName').value.trim();
				return true;
			} 
		}
	} else {
		obj.innerHTML = '检测中，请稍等...';
	}
}