AJAX autopopulate using PHP - php

Question

I am trying to populate two fields 'dep' and 'arr' when field 'flightnumber' is written into and 'onpointermove'.
Here is the form code:
<input type="text" name="flightnumber" id="flightnumber" onpointermove="showUser(this.value)" style="width: 70px;" maxlength="4">
<input type="text" name="dep" id="dep" style="width: 70px;">
<input type="text" name="arr" id="arr" style="width: 70px;">
Here is the AJAX
<script>
function showUser(str) {
if (str.length=="") {
document.getElementById("dep").innerHTML="";
document.getElementById("arr").innerHTML="";
return;
}
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
} else { // code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function() {
if (this.readyState==4 && this.status==200) {
var myObj = JSON.parse(this.responseText);
document.getElementById("arr").innerHTML = myObj.dep;
document.getElementById("dep").innerHTML= myObj.arr;
}
}
xmlhttp.open("GET","getdata.php?q=" + str,true);
xmlhttp.send();
</script>
And here is the php, which i have tested and does return correct results...
<?php
//look up the record based on email and get the firstname and lastname
$host_name = 'db5000091260.hosting-data.io';
$database = 'dbs85930';
$user_name = 'dbu68420';
$password = '';
$connect = mysqli_connect($host_name, $user_name, $password, $database);
$q = $_GET['q'];
$myObj->dep = "";
$myObj->arr = "";
$sql = "SELECT dep, arr FROM flights WHERE flightnumber = {$q}";
$result = mysqli_query($connect, $sql);
if (mysqli_num_rows($result) > 0) {
while($row = mysqli_fetch_assoc($result)) {
$myObj->dep = $row['dep'];;
$myObj->arr = $row['arr'];
$myJSON = json_encode($myObj);
echo $myJSON;
}
} else {
echo "0 results";
}
?>
I can only assume that the issue here is within the AJAX coding, as the PHP as mentioned is working.