https://www.idautomation.com/scripts/custom/basket.js

1//declare timer for basket form submit
2var timer = null;
3
4//see if auto update is enabled
5var autoUpdateEnabled = false;
6if ($("#quantity-auto-update"))
7{
8    autoUpdateEnabled = $("#quantity-auto-update").data("status");
9}
10
11// decrease quantity value in option list row
12$(function () {
13    $("body").on("click", "#basketContent button#row-qty-minus", function () {
14
15        var parentRow = $(this).closest("div");
16        var minusLink = $(parentRow).find("button#row-qty-minus").val()
17
18        var quantityField = $(parentRow).find("input#modal-qty");
19        var quantity = quantityField.val();
20
21        if (parseInt(quantity) > 1) {
22            quantityField.val(parseInt(quantity) - 1)
23
24            //set timer for basket form submit
25            if (autoUpdateEnabled && timer == null) {
26                timer = setTimeout(submitCart, 2000);
27            }
28        }
29    })
30});
31
32// increase quantity value in option list row
33$(function () {
34    $("body").on("click", "#basketContent button#row-qty-plus", function () {
35
36        var parentRow = $(this).closest("div");
37        var minusLink = $(parentRow).find("button#row-qty-plus").val()
38
39        var quantityField = $(parentRow).find("input#modal-qty");
40        var quantity = quantityField.val();
41        quantityField.val(parseInt(quantity) + 1)
42
43        //set timer for basket form submit
44        if (autoUpdateEnabled && timer == null) {
45            timer = setTimeout(submitCart, 2000);
46        }
47    })
48});
49
50function onBasketUpdate(response) {
51
52    // item updated/removed from cart
53    // update the basket and wishlist count in header 
54    if (typeof storeheadernavigation !== 'undefined') {
55        storeheadernavigation.refresh();
56    }
57    if (typeof storemenu !== 'undefined') {
58        storemenu.refresh(true);
59    }
60
61    //enable plus/minus buttons and reset the timer. 
62    if (autoUpdateEnabled) {
63        $("#basketContent button#row-qty-plus, #basketContent button#row-qty-minus").attr("disabled", false);
64        timer = null;
65    }
66
67
68}
69
70if (autoUpdateEnabled) {
71
72    function submitCart() {
73
74        //disable plus/minus buttons
75        $("#basketContent button#row-qty-plus, #basketContent button#row-qty-minus").attr("disabled", true);
76
77        //submit basket form
78        $('#IsCheckoutButton').val(0);
79        $("#basket-form").submit();
80    }
81
82    // submit basket form on loose focus
83    $('#basketContent input#modal-qty').blur(submitCart);
84
85    // pervent submit on enter key
86    $(document).on('keyup keypress', function (e) {
87        var keyCode = e.keyCode || e.which;
88        if (keyCode === 13 && e.target.id === "modal-qty") {
89            e.preventDefault();
90            submitCart();
91            return false;
92        }
93    });
94}