How to access id of the modal globally using JavaScript Laravel Laravel

I’m have an html table with modal column (see image below for your reference)
Order Modal

Upon click the Order modal, I can access the its ID using onclick event in JavaScript
(var customer_id = $(this).val();)

I wanted to access and used it in my Add function using ajax but I’m having an error of “customer_id is not defined” when I tried to use it. Is there a way to fix it or do it properly.

This is my script

<script>
        $(document).ready(function () {
            // START OPEN CART MODAL FUNCTION
                $(document).on('click', '.viewCart', function (e) {
                    e.preventDefault();
                    var customer_id = 0;
                    var customer_id = $(this).val();
                    console.log(customer_id);

                    $.ajax({
                        type: "GET",
                        url: "/get-cart/"+customer_id,
                        dataType: "json",
                        success: function (response) {

                            if (response.data != null) {
                                console.log(response);
                                $('.OrderTbody').html("");
                                $.each(response.data, function (key, item) {
                                    $('.OrderTbody').append('<tr>
                                        <td>' + item.p_name + '</td>
                                        <td>' + item.c_qty + '</td>
                                        <td class="total">' + item.p_amt + '</td>
                                    <td><button type="button" value="' + item.c_id + '" class="btn btn-danger deleteListBtn btn-sm">Delete</button></td>
                                    </tr>');

                                });


                            }
                        }
                    });
                });
            // END OPEN CART MODAL FUNCTION

            // START ADD DATA FUNCTION
                    $(document).on('click', '.addToCart', function (e) {
                        e.preventDefault();
                        var data = {
                            'store': $('.sel_store').val(),
                            'product': $('.sel_product').val(),
                            'quantity': $('.sel_qty').val(),
                            // HOW TO INPUT Customer ID here, I tried this but im having an error of
                            // customer_id is not defined
                            'customer_id': customer_id,

                        }
                        $.ajaxSetup({
                            headers: {
                                'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
                            }
                        });
                        $.ajax({
                            type: "POST",
                            url: "/cart-list",
                            data: data,
                            dataType: "json",
                            success: function (response) {

                            }
                        });

                    });
            // END ADD DATA FUNCTION

        });
        </script>