function ajax(url, params, completed) {
	$.ajax({
		type: "POST",
		url: url,
		data: params,
		dataType: "json",
		beforeSend: function(callback) {
			
		},
		error: function(XMLHttpRequest, textStatus, errorThrown) {
			//XMLHttpRequest.responseText
		},
		success: function(callback){
			if (typeof(completed) == 'function') 
				completed(callback);
		}
	});
}