javascript - 为什么 .change() 在 jquery 查询输入值更改后不执行

Question

$("body").on('change' , '.pp',function(){
    var price = $(".pp").val();
    price = parseInt(price);
    var quantity = $(".ss").val();
    quantity = parseInt(quantity);
    var amount = (price*quantity);
    $(".rr").val(amount);
    });
/* so from the about what i think is first value was 0 then it is changed to value assigned by the above jquery, until this its working fine but problem arises below, another jquery where severals amount(.pricing) are added and value is assigned to ("#totalAmount") */
    
     $(document).on('change', '.pricing', function() {
        var total=0;
        $(".pricing").each(function(){
            quantity = parseInt($(this).val());
            if (!isNaN(quantity)) {
                total += quantity;
            }
        });
        $("#totalAmount").val(total);
    });
/*  */

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- Lets suppose i have an input field which has value=0 as given in html -->
<input type="text" value="0" class="rr pricing" name="amount">

    <input type="text" class="ss" name="price">
    <input type="text" class="pp" name="qty">
<!-- Jquery used to set value of input[name="amount"] from these two inputs -->

除非我手动单击 .pricing 输入字段并手动更改它，否则它不会执行，我上面的 jquery 计算不应该更改它的值，因此理论上它应该执行，或者我做错了什么。

Answer 1

change 事件仅在用户更改某些内容时自动触发，而不是在 Javascript 更改内容时自动触发。您需要自己触发它。

更改行:

$(".rr").val(amount);

至:

$(".rr").val(amount).trigger("change");