Передача стоимости от начальной загрузки модального содержащих текстовое поле на ASP:TextBox в в formview, который связан

I have googled the hell out of this one and I just cant get any further forward, I have a button sitting in an ASP Formview, that calls a Bootstrap Modal that contains 2 textboxs. When the user clicks on the Enter button on the Modal it should call javascript function to transfer those 2 values to 2 ASP:Textbox's sitting on the Formview.

The JavaScript function is as follows:-

<pre lang="Javascript">
        $('#myModal').on('click', '.btn-primary', function () {
            var value = $('#chqNumber').val();
            var value2 = $('#chqAmount').val();
            $('#paymentIDTextBox').val(value);
            $('#paidAmountTextBox').val(value2);
            $('#myModal').modal('hide');
        });

<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModal" aria-hidden="true">
    <div class="modal-dialog" role="document">
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">×</span>
                </button>
                <h4 class="modal-title" id="exampleModalLabel">Input parameters</h4>
            </div>
            <div class="modal-body">

                    <div class="form-group">
                        <label for="recipient-name" class="form-control-label">Cheque Number:</label>
                        <input type="text" class="form-control" id="chqNumber" >
                    </div>
                    <div class="form-group">
                        <label for="message-text" class="form-control-label">Cheque Value:</label>
                        <input type="text" class="form-control" id="chqAmount">
                    </div>
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-secondary" data-dismiss="modal">
                    Close
                </button>
                <button id="paramsOkay" type="button" class="btn btn-primary">
                    Enter
                </button>
            </div>
        </div>
    </div>
</div>

I have put an alert box in the javascript function and that gets the right value, I have attempted to reference the ASP:textbox by client.ID, but cant get it to even pass muster in intelisense 

<pre lang="Javascript">
mytextbox = document.getElementById("<%= paymentIDTextBox.ClientID %>");