ajax success doesnt alert anything - php

Question

I have an AJAX request and if get id succeeds I would like to alert the data.
If I print_r my PHP function I get the correct result.
My ajax:
$.ajax({
type: "GET",
url: "getQuestions.php",
datatype: "json",
data:{
compid: id[4].innerHTML
},
success: function(response){
alert(response);
}
});
My getQuestions.php:
<?php
include "functions.php";
getQuestions($_GET['compid']);
My function getQuestions($compid) in functions.php:
function getQuestions($compid){
$int=intval($compid);
$vastus=array();
$conn = dbconnect();
$sql="SELECT * FROM bet_question WHERE compid = $int";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
array_push($vastus,$row);
}
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
return json_encode($vastus);
}
If I do print_r(getQuestions("some valid id")) in getQuestion.php I get valid result and if I do var_dump($_GET['compid']) in getQuestion I'll get the correct id from ajax request.
If I check if the request is sent using inspect elements I get that request is sent with correct params, but the response is empty.

Answer 1

Instead of return you need to use echo and it should be updated as
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
array_push($vastus,$row);
}
echo json_encode($vastus);
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
exit;

Answer 2

You don't have to return the data, use echo instead, and set content type:
function getQuestions( $compid ) {
$int=intval($compid);
$vastus=array();
$conn = dbconnect();
$sql="SELECT * FROM bet_question WHERE compid = $int";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
array_push($vastus,$row);
}
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
#header( 'Content-Type: application/json' );
echo json_encode( $vastus );
exit;
}
Hope it helps