Get the ID's of the html textboxes made by javascript using c#

so far i am successful making multiple html texboxes dynamically using a c# button but now i want to get the id's of those textboxes in codebehind(c#) in order to get their data and save it in the database. if i get a hint to get id's of textboxes then insertion in database is easy.

javascript code:

<script type="text/javascript">

        var counter = 0;

        function AddFileUpload() {

            var div = document.createElement('DIV');

            div.innerHTML = 

             'File Name: <input id="_txtFileName' + counter + '"  type="text" />' +

             'File Path: <input id="_txtFilePath' + counter + '" type="text" />' +

             '<input id="FileUpload' + counter + '" name = "FileUpload' + counter + '" type="file" />' +

             '<input id="Button' + counter + '" type="button" value="Remove" onclick = "RemoveFileUpload(this)" />';

            document.getElementById("FileUploadContainer").appendChild(div);

            counter++;

        }

        function RemoveFileUpload(div) {

            document.getElementById("FileUploadContainer").removeChild(div.parentNode);

        }

    </script>