How to use the @microsoft/signalr.HttpTransportType.LongPolling function in @microsoft/signalr

it("populates the Content-Type header when sending XMLHttpRequest", async (done) => {
        // Skip test on Node as this header isn't set (it was added for React-Native)
        if (typeof window === "undefined") {
            done();
            return;
        }
        const hubConnection = getConnectionBuilder(HttpTransportType.LongPolling, TESTHUB_NOWEBSOCKETS_ENDPOINT_URL)
            .withHubProtocol(new JsonHubProtocol())
            .build();

        try {
            await hubConnection.start();

            // Check what transport was used by asking the server to tell us.
            expect(await hubConnection.invoke("GetActiveTransportName")).toEqual("LongPolling");
            // Check to see that the Content-Type header is set the expected value
            expect(await hubConnection.invoke("GetContentTypeHeader")).toEqual("text/plain;charset=UTF-8");

            await hubConnection.stop();
            done();
        } catch (e) {
            fail(e);
        }

});
                    await hubConnection.start();
                    const response = await hubConnection.invoke("Echo", message);

                    expect(response).toEqual(message);

                    await hubConnection.stop();

                    done();
                } catch (err) {
                    fail(err);
                    done();
                }
            });

            if (transportType !== HttpTransportType.LongPolling) {
                it("terminates if no messages received within timeout interval", async (done) => {
                    const hubConnection = getConnectionBuilder(transportType).build();
                    hubConnection.serverTimeoutInMilliseconds = 100;

                    hubConnection.onclose((error) => {
                        expect(error).toEqual(new Error("Server timeout elapsed without receiving a message from the server."));
                        done();
                    });

                    await hubConnection.start();
                });
            }

            it("preserves cookies between requests", async (done) => {
                const hubConnection = getConnectionBuilder(transportType).build();
                await hubConnection.start();

export function getHttpTransportTypes(): HttpTransportType[] {
    const transportTypes = [];
    if (typeof window === "undefined") {
        transportTypes.push(HttpTransportType.WebSockets);
        transportTypes.push(HttpTransportType.ServerSentEvents);
    } else {
        if (typeof WebSocket !== "undefined") {
            transportTypes.push(HttpTransportType.WebSockets);
        }
        if (typeof EventSource !== "undefined") {
            transportTypes.push(HttpTransportType.ServerSentEvents);
        }
    }
    transportTypes.push(HttpTransportType.HttpStreaming);
    transportTypes.push(HttpTransportType.LongPolling);

    return transportTypes;
}