将GET变量从URL传递到.js，从.js传递到.php

Question

Hi I currently have a JS file being called to populate my html page with dynamic data. My JS file calls a PHP file to fetch stuff from my sqldb and my PHP file echos json_encode the stuff it got from the sqldb, which in turn is used to populate the html page.

My problem is that depending on what's in the url ie ?user=Bob, I want my js file to call the php file to search for Bob. Right now it searches for current user if ?user=xxxx is not specified. It seems the $GET['user'] is always null, thus it's not being passed because I suspect the JS file working as a middleman. Here are my code snippets:

My URL: www.website.com/index.php?user=Bob

My HTML Code

<script type="text/javascript" src="js/get-data.js"></script>

My JavaScript

$(document).ready(function(){
    $.ajax({
        type: 'GET',
        url: 'php/retrieve-db.php',
        dataType: 'json',
        success: function(response){
            var name = response[0];
            var location = response[1]; 

            $('#name').html(name);
            $('#location').val(location);
            }
    });
});

My PHP Code

$id;

if (isset($_GET["user"]))
{
    $id = $_GET["user"];
}
else
{
    $id = $_SESSION['loggedInUser'];
}

$query = "SELECT * FROM Persons WHERE User = '$user'";
if($result = mysqli_query($sqlconnection,$query))
{
    $row = mysqli_fetch_row($result);

    echo json_encode($row);
}

Answer 1

I believe you want to do something like this

$(document).ready(function(){
    $.ajax({
        type: 'GET',
        url: 'php/retrieve-db.php',
        data: <?php echo json_encode($_GET); ?>,
        dataType: 'json',
....

EDIT:
Thanks @Brad and @Ashwin Musjija for pointing out. I was focusing on answer too quickly that I overlook the possible non persistent XSS attack.