A minimal backend controller

index.ts

userService.change.subscribe((change) =>
    io.sockets.emit(SocketChannel.user, JSON.stringify(change))
);

app.post("/users/join", (req, res) => {
    try {
        res.json(userService.join(<User>req.body));
    } catch (error) {
        res.status(400).send(error);
    }
    console.log("join", req.body);
});

app.post("/users/leave", (req, res) => {
    try {
        res.json(userService.leave(<User>req.body));
    } catch (error) {
        res.status(400).send(error);
    }
    console.log("leave", req.body);
});

app.post("/users/position", (req, res) => {
    try {
        res.json(userService.position(<User>req.body));
    } catch (error) {
        res.status(400).send(error);
    }
});