function tao_doi_tuong()
{
	var xmlhttp;
	// Tai doi tuong tren trinh duyet Firefox va  Opera	
	if (!xmlhttp && typeof XMLHttpRequest != 'undefined') 
	{
		try 
		{
		  xmlhttp = new XMLHttpRequest();
		} 
		catch (e) 
		{
			alert("Trinh duyet cua ban khong ho tro XMLHTTPRequest");
			xmlhttp = false;
		}
	}
	// Tao doi tuong tren trinh duyet IE
	else
	{
	xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
	}
	return xmlhttp;
}
var yeucau = tao_doi_tuong();
function sever_interaction()
	{
	if(yeucau.readyState == 1)
		{
		document.getElementById('main_center').innerHTML = '';
		document.getElementById('main_center').innerHTML = '<center><img src=images/loading.gif>  Đang tải dữ liệu...</center><br>';
		}
	if(yeucau.readyState == 4)
		{
		var traloi = yeucau.responseText;
		document.getElementById('main_center').innerHTML = '';
		document.getElementById('main_center').innerHTML = traloi;
		}
	}
function guiyeucau()
		{
		var keyword = document.getElementById("keyword").value;
			if ( keyword == '')
				{
					//alert("Ban chua cho biet doan ma muon ma hoa");
					document.getElementById('main_center').innerHTML = '<center><img src=images/loading.gif>  Vui lòng nhập từ khóa cần tìm kiếm...</center><br>';
					return false;
				}
			var url = "ajax/search.php?type=text&keyword=" + encodeURI(keyword);
			yeucau.open("GET", url);
			yeucau.onreadystatechange = sever_interaction;
            yeucau.send(''); 
		}
function sever_request_form()
	{
	if(yeucau.readyState == 1)
		{
		document.getElementById('serch_result').innerHTML = '';
		document.getElementById('serch_result').innerHTML = '<center><img src=images/loading.gif>  Đang tải dữ liệu...</center><br>';
		}
	if(yeucau.readyState == 4)
		{
		var traloi = yeucau.responseText;
		document.getElementById('serch_result').innerHTML = '';
		document.getElementById('serch_result').innerHTML = traloi;
		}
	}
function search_form()
		{
		var keyword_form = document.getElementById("keyword_form").value;
		var menu = document.getElementById("menu").value;
			if ( keyword_form == '' )
				{
					//alert("Ban chua cho biet doan ma muon ma hoa");
					//alert(document.getElementById("menu").value);
					document.getElementById('serch_result').innerHTML = '<center><img src=images/loading.gif>  Vui lòng nhập từ khóa cần tìm kiếm...</center><br>';
					return false;
				}
			//alert(encodeURI(menu));
			//alert("ajax/search.php?type=text&keyword=" + encodeURI(keyword_form) + "&danhmuc=" + encodeURI(menu_form));
			var url = 'ajax/search.php?type=text&keyword=' + encodeURI(keyword_form) + '&danhmuc=' + encodeURI(menu);
			yeucau.open("GET", url);
			yeucau.onreadystatechange = sever_request_form;
            yeucau.send(''); 
		}