const servlet = (qs = '') => new Promise((resolve) => $.get(`myservlet${qs}`, {}, resolve, 'json'))

const chain = (data) => servlet(`?chain=${data.expected}`)

const tap = (effect) => (data) => {
    effect(data)
    return data
}

const show = (data) => console.info(data)

const logger = ({ steps }) => console.log(`Number of steps advanced is ${steps}`)

servlet()
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(logger))
    .then(tap(show))

package kz.edu.nu.cs.se;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.gson.Gson;

@WebServlet(urlPatterns = { "/myservlet" })
public class MyServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private Gson gson = new Gson();

    public MyServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        Random random = new Random();
        
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        
        if (request.getParameter("reset") != null) {
            request.getSession().invalidate();
        }

        MyPosition myPosition = (MyPosition) request.getSession().getAttribute("myPosition");

        String chain = request.getParameter("chain");

        if (myPosition == null) {
            Integer steps = Integer.valueOf(1);
            Integer expected = Integer.valueOf(random.nextInt(1000));
            request.getSession().setAttribute("myPosition", new MyPosition(steps, expected));
            myPosition = (MyPosition) request.getSession().getAttribute("myPosition");
        } else {
            if (chain != null) {
                if (Integer.parseInt(chain) == myPosition.expected.intValue()) {
                    request.getSession().setAttribute("myPosition", myPosition.advance(random.nextInt(1000)));
                    myPosition = (MyPosition) request.getSession().getAttribute("myPosition");
                }
            }
        }
        
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        out.append(gson.toJson(myPosition));
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

class MyPosition {
    public final Integer steps;
    public final Integer expected;
    
    public MyPosition(Integer steps, Integer expected) {
        this.steps = steps;
        this.expected = expected;
    }
    
    public MyPosition advance(int i) {
        return new MyPosition(this.steps + 1, i);
    }
}

const servlet = (qs = '') => new Promise((resolve) => $.get(`myservlet${qs}`, {}, resolve, 'json'))

const chain = (data) => servlet(`?chain=${data.expected}`)

const tap = (effect) => (data) => {
    effect(data)
    return data
}

const show = (data) => console.info(data)

const logger = ({ steps }) => console.log(`Number of steps advanced is ${steps}`)

servlet()
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(logger))
    .then(tap(show))

const withFont = (fontName) => {
    let font = null;
    getFont(fontName).then(f => font = f);
    
    return class Text {
        getFont() {
            return font;
        }
    };
};

const RobotoText = withFont('Roboto');

new RobotoText().getFont();

const withFont = (fontName) => {
    let font = null;
    getFont(fontName).then(f => font = f);
    
    return class Text {
        getFont() {
            return font;
        }
    };
};

const RobotoText = withFont('Roboto');

new RobotoText().getFont();