function tree(id, url) {
	var element = document.getElementById(id);

	function hasClass(elem, className) {
		return new RegExp("(^|\\s)"+className+"(\\s|$)").test(elem.className)
	}

	function toggleNode(node) {
		var newClass = hasClass(node, 'ExpandOpen') ? 'ExpandClosed' : 'ExpandOpen'
		var re =  /(^|\s)(ExpandOpen|ExpandClosed)(\s|$)/
		node.className = node.className.replace(re, '$1'+newClass+'$3')
	}

	function load(node) {

		function showLoading(on) {
			var expand = node.getElementsByTagName('DIV')[0];
			expand.className = on ? 'ExpandLoading' : 'Expand'
		}

		function onSuccess(data) {
			if (!data.errcode) {
				onLoaded(data)
				showLoading(false)
			} else {
				showLoading(false)
				onLoadError(data)
			}
		}
		function onAjaxError(xhr, status){
			showLoading(false)
			var errinfo = { errcode: status }
			if (xhr.status != 200) {
				errinfo.message = xhr.statusText
			} else {
				errinfo.message = 'Error in server data'
			}
			onLoadError(errinfo)
		}
		function onLoaded(data) {
			for(var i=0; i < data.length; i++) {
				var child = data[i];	
				var li = document.createElement('LI');
				li.id = child.id;
				li.className = "Node Expand" + (child.isFolder ? 'Closed' : 'Leaf');
				if (i == data.length-1) li.className += ' IsLast';
				li.innerHTML = '<div class="Expand"></div><div class="Content"><span>'+child.title+'</span></div>';
				if (child.isFolder) {
					li.innerHTML += '<ul class="Container"></ul>'
				}
				node.getElementsByTagName('UL')[0].appendChild(li)
			}
			node.isLoaded = true
			toggleNode(node)
		}
		function onLoadError(error) {
			var msg = "Error "+error.errcode
			if (error.message) msg = msg + ' :'+error.message
			alert(msg)
		}
		showLoading(true)
		$.ajax({
			url: url,
			data: {id: node.id},
			dataType: "json",
			success: onSuccess,
			error: onAjaxError,
			cache: false
		});
	}
	element.onclick = function(event) {
		event = event || window.event
		var clickedElem = event.target || event.srcElement
		if (hasClass(clickedElem.parentNode, 'Content')) {
			var a = clickedElem.parentNode.parentNode.id;
			js_ajax_text(a, 'categories');
			$(this).find('span').removeClass("active");
			clickedElem.className += ' active';
			return;
		}
		if (!hasClass(clickedElem, 'Expand')) {
			return;
		}
		var node = clickedElem.parentNode
		if (hasClass(node, 'ExpandLeaf')) {
			return;
		}
		if (node.isLoaded || node.getElementsByTagName('LI').length) {
			toggleNode(node);
			return;
		}
		if (node.getElementsByTagName('LI').length) {
			toggleNode(node);	
			return;
		}
		load(node)
	}
}