How can I modify this script so that it works when the page first loads AND on change?

I have a script that loads a dependent drop-down options. I added a part where the dependent drop-down hides whenever there are no options available. The primary drop-down retains the most recent submission data after being submitted, but when you submit an option that has no options on the secondary drop-down, and the page reloads, the primary drop-down, with the option that has no secondary options shows, and also the secondary drop-down, and when you click it it's just empty, because the logic that checks whether it should be hidden or not only checks when there's a change in the primary drop-down. How can I change this script at the end so that it loads both at the beginning and when there are changes?

enter_exit_area.html

{% extends "base.html" %}

{% load core_tags staticfiles %}

{% block main %}

    <form id="warehouseForm" action="" method="POST" data-stations-url="{% url 'operations:ajax_load_stations' %}" novalidate >
        {% csrf_token %}


        <div>
            <div>
                <label>Employee #</label>
                {{ form.employee_number }}

            </div>

            <div>
                <label>Work Area</label>
                {{ form.work_area }}
            </div>
            <div id="my-hidden-div">
                <label>Station</label>
                {{ form.station_number }}
            </div>
        </div>

        <div>
            <div>
                <button type="submit" name="enter_area" value="Enter">Enter Area</button>
                <button type="submit" name="leave_area" value="Leave">Exit Area</button>
            </div>
        </div>
    </form>

    <script>
        $("#id_work_area").change(function () {
            var url = $("#warehouseForm").attr("data-stations-url");
            var workAreaId = $(this).val();
            var $stationNumberField = $("#{{ form.station_number.id_for_label }}");

            $.ajax({
                url: url,
                data: {
                    'work_area': workAreaId
                },
                success: function (data) {
                    $("#my-hidden-div").show(); // show it
                    $stationNumberField.html(data);
                    // Check the length of the options child elements of the select
                    if ($stationNumberField.find("option").length === 1) {
                        $stationNumberField.parent().hide(); // Hide parent of the select node
                    } else {
                        // If any option, ensure the select is shown
                        $stationNumberField.parent().show();
                    }
                }
            });
        });
     </script>

{% endblock main %}