php - Can I use a jQuery Ajax request in Code Snippets Plugin for Wordpress?

one text

I am using the Code Snippets Plugin for WordPress to send a jQuery Ajax request but I keep receiving a

POST https://mywebsite.com/wp-admin/admin-ajax.php 400 (Bad Request)

I have tried what seems to be a thousand ways to formulate the Ajax request following examples from stackoverflow, jQuery forums, WordPress forums, and it goes on. Always with the same error.

Here is what I currently have in my Snippet editor: JavaScript code

var jq = jQuery.noConflict();
// a bunch of code to determine what day is selected on a calendar, this all works up until the ajax call
jq(".c-day-content").click(function () {
    console.log ("handled the day being picked quite nicely...");
        day = jq(this).text();
        day = day.replace(/[^0-9]/g,'');
        console.log("day=" + day);
    bookingStart = bookingStart.concat(day);
    //query the db looking for time slots with appointments and returning this array

    var ajaxurl = '<?php echo admin_url( 'admin-ajax.php' ) ?>';
    console.log(ajaxurl);

    jq.ajax({
        url: ajaxurl,
        data: {
            action: "retrieveAttendees",
            dateSelected: bookingStart //bookingStart is variable that has a string value
        },
        method: 'POST',
        success: function(data, XMLHttpRequest) {
            //never been able to make it to here
            console.log(JSON.stringify(data));
        },
        error: function (XMLHttpRequest, textStatus, errorThrown) {
            console.log("we failed again: " + JSON.stringify(XMLHttpRequest));
            console.log("text status: " + textStatus);
            console.log("errorThrown: " + errorThrown)
        }
    }); 

Then my php handler inside the same snippet editor:

function retrieveAttendees_request() {
console.log("made it to the ajax request"); // I've never made it here either
if ( isset($_REQUEST)) {
    $bookingDay = $_REQUEST['dateSelected'];
    global $wpdb;
    $sql = $wpdb->prepare("select apps.bookingStart, COUNT(*) as booked from wp_amelia_customer_bookings as books inner join wp_amelia_appointments as apps on books.appointmentId = apps.id where apps.bookingStart like %s'%' and apps.status = 'approved' GROUP BY books.appointmentId;", $bookingDay);
    $result = $wpdb->get_row($sql, ARRAY_A);
    echo json_encode($result);
}
  die();
}
add_action('wp_ajax_retrieveAttendees', 'retrieveAttendees_request');
add_action('wp_ajax_nopriv_retrieveAttendees', 'retrieveAttendees_request');

I have tried adding the dataType to the Ajax, no luck. Tried adding both dataType and ContentType, no luck. I have no clue as to why I keep getting the same POST 400 Bad Request error. I would appreciate any help and insight.