Send my ajax text field to php input value

Hi am trying to send my ajax value into my php field but when i try to make changes i always gets the blank input field

this is my form

<div id="paymentDetail" style="display: none">
                <center>
                    $count=0;
                    <form method="post" action="">
                        
                    @foreach($product as $input)
                    <div>Product: <span class="product"><input type="text" name="product[]" value=""></span></div>
                    <div>paymentID: <input type="text" class="paymentID" name="txn_id" value=""></div>
                    <div>paymentDate: <span class="paymentDate" name="date"></span></div>
                    @endforeach
                    <div>Print: <span><input type="submi" name="print" value="Print Order Summary"></span></div>
                    </form>

                </center>
            </div>

this is the script i am using

function demoSuccessHandler(transaction) {
        // You can write success code here. If you want to store some data in database.
        $("#paymentDetail").removeAttr('style');
        $('.paymentID').value(transaction.razorpay_payment_id);
        var paymentDate = new Date();
        $('.paymentDate').text(
                padStart(paymentDate.getDate()) + '.' + padStart(paymentDate.getMonth() + 1) + '.' + paymentDate.getFullYear() + ' ' + padStart(paymentDate.getHours()) + ':' + padStart(paymentDate.getMinutes())
                );

        $.ajax({
            method: 'post',
            url: "{!!route('dopayment')!!}",
            data: {
                "_token": "",
                "razorpay_payment_id": transaction.razorpay_payment_id
            },
            complete: function (r) {
                console.log('complete');
                console.log(r);
            }
        })
    }

via Chebli Mohamed