How can I get PHP function return data value in ajax

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Javascript

PHP

jQuery

i know this is too easy and i do more but this time i don't have any solution for it
it always return empty string and if i print_r $x it print correct value

function call()
{
    $db_host     = 'localhost';
    $db_user     = 'root';
    $db_pass     = '';
    $db_database = 'peoplex'; 
    /* End config */
    $db = new PDO('mysql:host='.$db_host.';dbname='.$db_database, $db_user, $db_pass);
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
    $result = $db->prepare("SELECT id,snap_url FROM live");
    $result->execute();
    $row= $result->fetch();
    // print_r($row['id']+2);
    return '<p>'+$row['id']+'</p>';
}

$x =''; 

if(isset($_GET['action']))
{ 
    //print_r("hhh");
    $GLOBALS["x"] = call();
    //print_r($GLOBALS["x"]);
    return $GLOBALS["x"];
}

<div id="live">t</div>

$( document ).ready(function() {
  console.log( "ready!" );
  start();
});

var i = 0;
function start()
{
    setInterval( function() {
        $.ajax({
            //  cache: false,
            type: "GET",
            url: "channel.php",
            datatype: "text",
            data: 'action=call',
            success: function (x, status, xhr)
                {
                    console.log(x);
                    document.getElementById('live').innerHTML =x;
                }
        }); // Ajax Call
    } //event handler
    ,33); //document.ready
}

What I have tried:

i use above code but did't run