$ is not defined on my javascript with multiple function and ajax inside each function

Question

Im am using Microsoft Edge in the scenario.

I as able to successfully do a single function with a ajax syntax with this code:

<script>
    document.getElementById("inputEventID").onchange = function () { myFunction() };

    function myFunction() {
        $.ajax({
        type: 'post',
        url: 'webFetchMax.php',
        data: {
            eventID: form.eventID.value
        },
        success: function (response) {
            $('#divSlots').html(response);
        }
    });
    }
</script>

However when I insert addition functions with their on ajax inside the function I am receiving $ is not defined error function monitorOccupy() as shown below:

<script>
    document.getElementById("inputEventID").onchange = function () { myFunction() };

    monitorOccupy();
    monitorAvail();
    function monitorOccupy() {
        $.ajax({
        type: 'post',
        url: 'webFetchMax.php',
        data: {
            eventID: form.eventID.value
        },
        success: function (response) { 
            $('#oSlots').html(response);
        },
        complete: function() {
            setTimeout(monitorOccupy,1000);
        }
    });
    }
    function monitorAvail() {
    }

    function myFunction() {
        $.ajax({
        type: 'post',
        url: 'webFetchMax.php',
        data: {
            eventID: form.eventID.value
        },
        success: function (response) {
            $('#divSlots').html(response);
        }
    });
    }
</script>

I have no idea my is this error is showing up on my console.

Answer 1

Call these functions as below

$(document).ready(function(){ monitorOccupy(); MonitorAvail(); });

Answer 2

Before posting this question the only jQuery file in my html file was jquery.min.js

<script scr="https://ajax.googleapis.com/ajax/libs/jquery/3.2.0/jquery.min.js"></script>

After inserting another jquery.min.js file my problem is solved. This is what it looks now:

<script scr="https://ajax.googleapis.com/ajax/libs/jquery/3.2.0/jquery.min.js"></script>
<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>