How to prevent saving data when ajax response is false? - php

Question

I created a text filed for customer name. Already registered customer will show while clicking that text field. Only that registered customer can entry the data. I used ajax for prevent the new user addition.
this is the ajax:
function validateForm()
{
var customerName = document.getElementById('customerName').value;
var customerId = document.getElementById('customerId').value;
var getResponse=0;
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
// document.getElementById("txtHint").innerHTML = xmlhttp.responseText;
getResponse= xmlhttp.responseText;alert(getResponse);
if(getResponse=="0")
{
return false;
}
}
};
xmlhttp.open("GET", "customer_check_ajax.php?name="+customerName+"&id="+customerId, true);
xmlhttp.send();
}
and here is the ajax page customer_check_ajax.php :
<?php
require("../../config/config.inc.php");
require("../../config/Database.class.php");
require("../../config/Application.class.php");
if($_SESSION['travelType']=='Admin')
{
$check = 1;
}
else
{
$check = '';
$logId = $_SESSION['travelId'];
$proId = $_SESSION['proId'];
$check = "proId='$proId'";
}
$cusName = $_REQUEST['name'];
$cusId = $_REQUEST['id'];
$connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS, DB_DATABASE);
$qry="select * FROM ".TABLE_ACCOUNTS." WHERE ID='$cusId' and accountName='$cusName' and proId='$proId'";
$res = mysqli_query($connection, $qry);//echo $qry;
$num = mysqli_num_rows($res);
if($num>0)
echo '1';
else
echo '0';
?>
here i would get the responses as 0 for new user and 1 for already registered user. But i want to stop saving data when new user addition. Please help me.

Answer 1

You are making Asynchronous request and the answer of the ajax will come after the function is over ..
To do what you want you must do synchronous ajax request
xmlhttp.open("GET", "customer_check_ajax.php?name="+customerName+"&id="+customerId, false); // `false` makes the request synchronous