Why does express session kill the session when the application is idle?

Question

Node.js

I use express-session in my app:

app.use(session({
  genid: function(req) {
    return uuid.v4();
  },
  saveUninitialized: false,
  resave: false,
  cookie: { 
    name: config.get('session_cookie_name'),
    maxAge:  (60*60*1000*24) // Сутки
  } , 
  key: config.get('session_cookie_name'),
  secret: config.get('session_cookie_secret'),
  proxy: true,
  store: MongoStore
}));

But once you open a tab and forget about it for half an hour, the session ends. How so?

Answer 1

https://github.com/expressjs/session#resave