ajax调用php只对mysql进行插入

I need to call a php file from a javscript function by ajax and do an insert in a table on load my page. I´m doing this but the javascript function call my php file and when end the execution of all the sentences on the php file not return to my javascript funtion only show a withe page.

I don't want to return any value form the php file...only finish that insert and charge the of the page that is contains in the same file php that conteins the javascripts functions.

The call to the files is doing by the function "guardar_alerta" and this call to "realizar_peticion"

function realizar_peticion(url, metodo, funcion)
{
  peticionHTML.onreadystatechange = funcion;
  peticionHTML.open(metodo, url, true);
  peticionHTML.send(null);
}

function guardar_alerta(lat)
{
  realizar_peticion("../sites/all/modules/custom/gestion_usuarios/includes/usuario/aviso.php?lat="+lat,"GET",funcion_actuadora);
}

Here the Javascript code

function inicializar_XHR()
{
  if(window.XMLHttpRequest)
    peticionHTML = new XMLHttpRequest();
  else
    peticionHTML = new ActiveXObject("Microsoft.XMLHTTP");
}

function realizar_peticion(url, metodo, funcion)
{
  peticionHTML.onreadystatechange = funcion;
  peticionHTML.open(metodo, url, true);
  peticionHTML.send(null);
}

function guardar_alerta(lat)
{
  realizar_peticion("../sites/all/modules/custom/gestion_usuarios/includes/usuario/aviso.php?lat="+lat,"GET",funcion_actuadora);
}

function funcion_actuadora() {
  if(peticionHTML.readyState == 4)
    if(peticionHTML.status == 200)
      alert("IS done!");
}

function sendToPhp()
{
      var lat = position.coords.latitude;
      inicializar_XHR();
      guardar_alerta(lat);

}

this is the php file that is call by ajax ...aviso.php

<?php
$lat = $_GET['lat'];

$con = mysqli_connect("localhost", "root", "", "delmontag");
if (!$con) {
    die('Could not connect: ' . mysqli_error());
}

//$sql_query = "SELECT * FROM dt_producto";
$sql_query="INSERT INTO dt_aviso (id_producto, latitud) VALUES(1, '4666663')";
mysqli_query($con, $sql_query);

mysqli_close($con);

?>

Thanks for all yours answers.

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