运行出错
调用express-session时，报错
express-session deprecated undefined resave option; provide resave option app.js:63:9 express-session deprecated undefined saveUninitialized option; provide saveUninitialized option app.js:63:9
In your configuration to session, you need to specify the resave and the saveUninitialized options to the value you want to use.
See https://github.com/expressjs/session#options for their values and meanings.
Example:
app.use(session({ secret: cookie_secret, name: cookie_name, store: sessionStore, // connect-mongo session store proxy: true, resave: true, saveUninitialized: true }));