how to use guacamole-common-js to get client command on ssh/rdp session to text file

Question

We want to save the user's keyboard movements using guacamole-common-js to receive the commands of the user as a string, not as a keylogger(keysym).For instance, when the user writes ls -l command, guacamole writes on console 108,115,32,45,108(https://www.tcl.tk/man/tcl8.4/TkCmd/keysyms.html). However, we want to get ls -l line, as the user press enter key on the client-side. Moreover, as we search guacamole-common-js, we found functions such as OutputStream, StringWriter, StringWriter, etc. Unfortunately, we didn't find any documentation about these functions which are in all.min.js

Thank you in advance!

  <script type="text/javascript">

        var display = document.getElementById("display");

        // Instantiate client, using an HTTP tunnel for communications.
        var guac = new Guacamole.Client(
            new Guacamole.WebSocketTunnel("ws://localhost:8080")
        );

        // Add client to display div
        display.appendChild(guac.getDisplay().getElement());

        // Error handler
        guac.onerror = function (error) {
            console.log(error);
        };

        // Connect

     
        guac.connect("token=v81l2bdBf6Qpbejs21AWUvuUb9vqMBO4yGNGN-olCFmGbioQmEVfSVJTCQrBArX-Qyp2kbsv7GkefpBGeGq-YQX4QQ0ofYJonmmQ5WyR9JmxulBnEwBDSgHkyVCW-2tP");
        // Disconnect on close
        window.onunload = function () {
            guac.disconnect();
        }

        // Mouse
        var mouse = new Guacamole.Mouse(guac.getDisplay().getElement());

        mouse.onEach(['mousedown', 'mouseup', 'mousemove'], function sendMouseEvent(e) {
            guac.sendMouseState(e.state);
        });


        // Keyboard
        var keyboard = new Guacamole.Keyboard(document);

        keyboard.onkeydown = function (keysym) {             
            guac.sendKeyEvent(1, keysym);

        };

        keyboard.onkeyup = function (keysym) {
            guac.sendKeyEvent(0, keysym);
        };

        var xxx=Guacamole.InputStream(guac);
       
        console.log('text---' + xxx);
       

        //function foo(stream , mimetype) {
        //    if (/^text\//.exec(mimetype)) {
        //        var stringReader = new Guacamole.StringReader(stream);
        //        console.log('stringReader---'+stringReader);
        //        var json = "";
        //        stringReader.ontext = function ontext(text) {
        //            json += text
        //            console.log('text---' + text);
        //        }


        //        stringReader.onend = function () {
        //            guac_client.clipboardData = '';
        //            guac_client.clipboardData = json;
        //        }
        //    }
        //}
       

        //array_reader.ondata = function (buffer) {

        //    // Decode UTF-8
        //    var text = utf8Parser.decode(buffer);

        //    // Call handler, if present
        //    if (guac_reader.ontext)
        //        guac_reader.ontext(text);

        //};

        //// Simply call onend when end received
        //array_reader.onend = function () {
        //    if (guac_reader.onend)
        //        guac_reader.onend();
        //};

        /* ]]> */</script>