How to validate if there is data within a date range, if not, send message

I need that when selecting the date range by means of datepicker , verify if there is data or not within the range when executing the query in the file php , if there are not any send a message. Since there is no data, it will not generate a PDF.

This is in my function js :

 function Report(fecha1,fecha2,status)
    {

   var fecha1 =document.getElementById("start").value;
   var fecha2 =document.getElementById("end").value;

      if()//valida si la consulta tiene datos desde el rango seleccionado
       {

       }  


    //solamente valida si estan vacios los campos
    if (fecha1 == ''  || fecha2 == '') {
        $("#fecha1").parent().addClass('has-error');
        $("#fecha2").parent().addClass('has-error');

        document.getElementById("errorMessageDate").style.display = "block";
        document.getElementById("errorMessageDate").innerHTML = "Ingresa una fecha valida.";
        document.location.href="#errorMessageDate";
    }
    else
    {
          setTimeout(function(){ window.open("http://localhost/WareHouse/outputReport.php?fecha1="+fecha1+"&fecha2="+fecha2+"&status="+status, "_blank"); }, 1000);
             $('#myModalReport').modal('hide');initArticles();
            console.log(fecha1);
            console.log(fecha2);
                }
    }

Check the information, from the php file:

if(isset($_GET['fecha1']) && isset($_GET['fecha2']) && isset($_GET['status']))
{
  $fecha1 = date('Y-m-d', strtotime(str_replace('/','-',$_GET['fecha1'])));
  $fecha2 = date('Y-m-d', strtotime(str_replace('/','-',$_GET['fecha2'])));
  $fecha1 = $_GET["fecha1"];
  $fecha2 = $_GET["fecha2"];
  $status = $_GET["status"];

  //Trae todos los item que esten por debajo de su minimo en stock.
  $connection = new MySqlServerConnection();
  $query =  "SELECT i.description_item,io.quantity_s,i.reorder_level,i.target_Stock,
            io.observations,io.registerDate_Output ,l.name_location,i.status,c.name_category,io.employee
            FROM inventory_output AS io
            INNER JOIN inventory_list AS i ON numFile = fkInventory
            INNER JOIN category as c on id_category = fkInventory
            INNER JOIN location as l on id_location = name_area
            WHERE io.registerDate_Output BETWEEN '".$fecha1."' AND '".$fecha2."' AND i.status = 1";

  $result = $connection->executeQuery($query,array($fecha1,$fecha2,$status));
  if ($result > 0) {...}