php ajax request don't give any response or error - php

Question

I've been trying to grab a username based on registered email when user enters his email and click on a button I've provide two data to my ajax request first is [cf] which identify which portion of code should be processed and second is the email but when clicking the button nothing happens and no errors appear in the console only when I open the page that have the php code of ajax request it says "Notice: Undefined variable: funcCall in D:\XAMPP\htdocs\lahj\framework\signin.php on line 19"
Here I will provide my code for ajax:
$("#login-next-btn").click(function(){
if(!$("#signin-email").val().trim()){
var email = $("#signin-email").val().trim();
$.ajax({
url: "framework/signin.php",
type: "POST",
data: {cf:'cf1',email:email},
dataType:"json",
success: function(data){
if(data.result != "0")
{
alert("helo");
$("#signin-box-header p:first-of-type").text("مرحبًا");
$("#signin-box-header p:last-of-type").remove();
$("#signin-box-header").append("<p id='sigin-email-display'>"+data.result+"</p>");
$("#first-loader").fadeOut(600,function(){
$("#second-loader").css({"display":"flex"}).fadeIn(400);
});
}
else
{
alert("fail");
}
}
});
}
});
and here is my php code in a file called signin.php in a folder called framework:
<?php
ini_set( 'error_reporting', E_ALL );
ini_set( 'display_errors', true );
include_once 'db.php';
$email = null;
$funcCall = null;
if(isset($_POST['email']))
{
$email = $_POST['email'];
}
if(isset($_POST['cf']))
{
$funcCall = $_POST['cf'];
}
if($funcCall == 'cf1' && !empty($email))
{
try
{
$database = new db();
$db = $database->openConnection();
$stmt = $db->prepare("select userName from khUsers where email = ?");
$stmt->execute(array($email));
$usersName = $stmt->fetchColumn();
$data = array('result' => $usersName);
echo json_encode($data);
}
catch (PDOException $e)
{
echo "There is some problem in connection: " . $e->getMessage();
$data = array('result' => "0");
echo json_encode($data);
}
}
?>

Answer 1

Add exit() function at the end of json_encode() function. it will show you result/error on your request in console.
if($funcCall == 'cf1' && !empty($email))
{
try
{
$database = new db();
$db = $database->openConnection();
$stmt = $db->prepare("select userName from khUsers where email = ?");
$stmt->execute(array($email));
$usersName = $stmt->fetchColumn();
$data = array('result' => $usersName);
echo json_encode($data); exit();
}
catch (PDOException $e)
{
echo "There is some problem in connection: " . $e->getMessage();
$data = array('result' => "0");
echo json_encode($data); exit();
}
}