Kevin Powell - Community•3d ago

How to keep track when session expires in express session

Hello guys, sorry to disturb you all; can someone explain how can I do in order to keep track when a session expires , for e,g after 5sec without refreshing the web-page

// Access the session as req.session
app.get('/', (req,res) => {
    console.log(req.session);
    if (req.session.viewCount) {
        req.session.viewCount++;
        viewCount++;
    }
    else {
        req.session.viewCount = 1;
        viewCount = 1;
    }
    console.log(`${req.session.id}`);
    res.send(`<h1> Hello world...view count(s): ${req.session.viewCount}`);
});

// Access the session as req.session
app.get('/', (req,res) => {
    console.log(req.session);
    if (req.session.viewCount) {
        req.session.viewCount++;
        viewCount++;
    }
    else {
        req.session.viewCount = 1;
        viewCount = 1;
    }
    console.log(`${req.session.id}`);
    res.send(`<h1> Hello world...view count(s): ${req.session.viewCount}`);
});

12 Replies

FakerOP•3d ago

The session expires after 5sec but I want to be redirected to kind of a "time-out" page because the user don't know that the session has expired

ἔρως•2d ago

how do you know that the session expires in 5 seconds? and why do you want to send users to a page every 5 seconds?

Jochem•2d ago

I'm going to assume you mean 5 seconds as an example that's easy to test. There's a couple of common ways: Either you redirect on the first failed request after the session expires, or you keep track of the session time in both the frontend and the backend. For the first option, usually that's fine because the user doesn't really care whether the session is still alive if they're not doing anything with the site. For the second option, the reason you keep track of it on both ends is that generally speaking once a page is loaded or an api call made and responded to, there's no further connection to the client. Any action by the user will create a new connection, but the server has no path to that user. You track the time in the browser and handle the expiration in the frontend because you can have continuously running code there. the very simple way is to send a timestamp of expiry along to the frontend so that you can set a timeout of the appropriate length and do what you need to do on the frontend but like I said, usually you just do the first option and not really worry about it the only time I'd use the second option, is if I was using a token that has an expiring access token and a refresh token

FakerOP•2d ago

I set the maxAge of cookie to 5000ms, it's for testing Yep I see, I will try it out and revert back, thanks ! There is something known as "keep-alive" , I think it is some kind of attribute in headers, do that have anything to play with what you mentioned please

Jochem•2d ago

In that is a similar concept but no more than that

ἔρως•2d ago

thats for http 1.1, to keep the tcp connection alive so it doesnt have to do all the dns and ssl/tsl handshake stuff again that wont do anything for you

FakerOP•2d ago

yep I see, so I can just ignore the "keep-alive" thing ?

Jochem•2d ago

yeah

FakerOP•2d ago

by the way, I was able to do the session management session !!

import express from 'express';
import session from 'express-session';
import path from 'path';
import { fileURLToPath } from 'url';

const app = express();
const port = 8080;
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
let viewCount = 0;


// Use the session middleware
const sessionOptions = {
    secret: 'super secret secret',
    cookie: {maxAge: 8000} // 5sec
    // resave: false, // don't save session for each request if unmodified
    // saveUninitialized: false // don't create session until something is stored - interacting with session
}
app.use(session(sessionOptions));

// Access the session as req.session
app.get('/', (req,res) => {
    console.log(req.session);
    if (req.session.viewCount) {
        req.session.viewCount++;
        viewCount++;
    }
    else {
        req.session.viewCount = 1;
        viewCount = 1;
    }
    console.log(`${req.session.id}`);
    res.sendFile(path.join(__dirname, '../public/HTML/index.html'));
});

app.get('/data', (req,res) => {
    if (!req.session.viewCount) {
        return res.status(440).json({
            "errorMsg": "Server timed out"
        });
    }
    res.json({
        "name":"John Doe",
        "age": 40
    })
})


app.listen(port, () => {
    console.log(`Server started on port: ${port}`);
})

import express from 'express';
import session from 'express-session';
import path from 'path';
import { fileURLToPath } from 'url';

const app = express();
const port = 8080;
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
let viewCount = 0;


// Use the session middleware
const sessionOptions = {
    secret: 'super secret secret',
    cookie: {maxAge: 8000} // 5sec
    // resave: false, // don't save session for each request if unmodified
    // saveUninitialized: false // don't create session until something is stored - interacting with session
}
app.use(session(sessionOptions));

// Access the session as req.session
app.get('/', (req,res) => {
    console.log(req.session);
    if (req.session.viewCount) {
        req.session.viewCount++;
        viewCount++;
    }
    else {
        req.session.viewCount = 1;
        viewCount = 1;
    }
    console.log(`${req.session.id}`);
    res.sendFile(path.join(__dirname, '../public/HTML/index.html'));
});

app.get('/data', (req,res) => {
    if (!req.session.viewCount) {
        return res.status(440).json({
            "errorMsg": "Server timed out"
        });
    }
    res.json({
        "name":"John Doe",
        "age": 40
    })
})


app.listen(port, () => {
    console.log(`Server started on port: ${port}`);
})

I don't know if it is efficient but it worked and I understand how things work :c I use the first method where we have invalid request... seems easier for now

ἔρως•2d ago

depends... but for this, you can ignore it dont forget that the session can be terminated in multiple ways: - client clears the cookies - the client doesnt communicate to the site for longer than the timeout - the client has an invalid session token - the server is restarted/restored/reverted - an automatic task clears "useless" cookies

FakerOP•2d ago

yep I see, what is the last point, for the automatic clask, didn't know it exist

ἔρως•2d ago

im not sure if it exists for express js, but it does for other languages

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How to keep track when session expires in express session