function chklogin()    
{   
	var userid= document.form1.userid.value;   
	var pwd = document.form1.userpass.value;       
	userid= userid.replace(/^\s*|\s*$/g,"");   
	pwd = pwd.replace(/^\s*|\s*$/g,"");   
	if (userid=="" || pwd=="") {   
		window.alert("用户名和密码不能为空！");   
		return false;   
	}   
	return true;   
}