WebFund 2013F: Tutorial 7

Today you should spend your time understanding the following code. This is a complete node application. Consider the following:

• What does each line do? Specifically, what errors/loss of functionality would you lose if you remove any line?
• What node functionality has been omitted from this application relative to the other ones we have covered this term?
• How would you get this application to run?
• Where are functions being defined? Called?
• What is the control flow of this application? How does control pass between the browser and the application server? What functions are called at each stage?

The midterm will primarily cover this code. So this is your chance to prepare. Good luck!

package.json

{
  "name": "application-name",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node app.js"
  },
  "dependencies": {
    "express": "3.4.0",
    "jade": "*"
   }
}

app.js

var express = require('express'), http = require('http'),
    app = express();

var i, theRoom, loggedInUsers = {};
var rooms = { activeRooms: ['sickbay', 'engineering'],
              engineering: { title: "Engineering", roomExits: ['sickbay'] },
              sickbay: { title: "Sickbay", roomExits: ['engineering'] } };

function index(req, res) {
    if (req.session.player) {
        res.redirect("/" + req.session.currentRoom);
    } else {
        res.render('index', { title: 'COMP 2406 Small Adventure Demo', 
                              error: req.query.error }); }}

function start(req, res) {
    req.session.player = req.body.player;
    res.redirect("/engineering") }

function quit(req, res) {
    req.session.destroy();
    res.redirect("/"); }

function makeRoomHandler(name, contents) {
    handler = function(req, res) {
        if (req.session.player) {
            req.session.currentRoom = name;
            res.render("room.jade", {title: contents.title,
                                     roomExits: contents.roomExits,
                                     player: req.session.player});
        } else { res.redirect("/"); }}
    return handler; }

app.set('port', process.env.PORT || 3000);
app.set('views', __dirname);
app.set('view engine', 'jade');
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.cookieParser('COMP2406 is confusing!'));
app.use(express.session());

app.get('/', index);
app.post("/start", start);
app.post("/quit", quit);
for (i = 0; i<rooms.activeRooms.length; i++) {
    theRoom = rooms.activeRooms[i];
    app.get('/' + theRoom,
            makeRoomHandler(theRoom, rooms[theRoom])); }

http.createServer(app).listen(app.get('port'), function(){
    console.log('Express server listening on port ' + app.get('port')); });

room.jade

doctype 5
html
  head
    title= title
  body
    h1= title
    p You're on a ship, player.
    p Go to:
    ul
      each theExit in roomExits
        li
          a(href= theExit) #{theExit}
    form(action="/quit", method="post")
      button(type="submit") Quit

index.jade

doctype 5
html
  head
    title= title
  body
    h1= title
    p Welcome to the #{title}
    p Please choose your player name
    div
      form(action="/start", method="post")
          div
            input(type="text", name="player")          
            label.add-on(for="player") Player Name
          button(type="submit") Start