btcpayserver/BTCPayServer/wwwroot/js/WalletSendLedger.js

$(function () {
    var psbt = $("#PSBT").val();
    var hintChange = $("#HintChange").val();
    var websocketPath = $("#WebsocketPath").val();
    
    var loc = window.location, ws_uri;
    if (loc.protocol === "https:") {
        ws_uri = "wss:";
    } else {
        ws_uri = "ws:";
    }
    ws_uri += "//" + loc.host;
    ws_uri += websocketPath;
    var ledgerDetected = false;
    var bridge = new ledgerwebsocket.LedgerWebSocketBridge(ws_uri);
    function WriteAlert(type, message) {
        $("#walletAlert").removeClass("alert-danger");
        $("#walletAlert").removeClass("alert-warning");
        $("#walletAlert").removeClass("alert-success");
        $("#walletAlert").addClass("alert-" + type);
        $("#walletAlert").css("display", "block");
        $("#alertMessage").text(message);
    }

    function Write(prefix, type, message) {

        $("#" + prefix + "-loading").css("display", "none");
        $("#" + prefix + "-error").css("display", "none");
        $("#" + prefix + "-success").css("display", "none");

        $("#" + prefix + "-" + type).css("display", "block");

        $("." + prefix + "-label").text(message);
    }

    var updateInfo = function () {
        if (!ledgerDetected)
            return false;
        $(".crypto-info").css("display", "block");
        var args = "";
        args += "&psbt=" + encodeURIComponent(psbt);
        args += "&hintChange=" + encodeURIComponent(hintChange);
        
        WriteAlert("warning", 'Please validate the transaction on your ledger');      

        var confirmButton = $("#confirm-button");
        confirmButton.prop("disabled", true);
        confirmButton.addClass("disabled");

        bridge.sendCommand('sendtoaddress', args, 60 * 10 /* timeout */)
            .catch(function (reason) {
                WriteAlert("danger", reason);
                confirmButton.prop("disabled", false);
                confirmButton.removeClass("disabled");
            })
            .then(function (result) {
                if (!result)
                    return;
                confirmButton.prop("disabled", false);
                confirmButton.removeClass("disabled");
                if (result.error) {
                    WriteAlert("danger", result.error);
                } else {
                    $("#PSBT").val(result.psbt);
                    $("#broadcastForm").submit();
                }
            });
    };

    bridge.isSupported()
        .then(function (supported) {
            if (!supported) {
                Write('hw', 'error', 'U2F or Websocket are not supported by this browser');
            }
            else {
                bridge.sendCommand('test', null, 5)
                    .catch(function (reason) {
                        if (reason.name === "TransportError")
                            reason = "Are you running the ledger app with version equals or above 1.2.4?";
                        Write('hw', 'error', reason);
                    })
                    .then(function (result) {
                        if (!result)
                            return;
                        if (result.error) {
                            Write('hw', 'error', result.error);
                        } else {
                            Write('hw', 'success', 'Ledger detected');
                            $("#sendform").css("display", "block");
                            ledgerDetected = true;
                            updateInfo();
                        }
                    });
            }
        });
});