By default, nested routers do not get passed any parameters that are used in mountpaths from their parent routers.

In your case, app is the parent router, which uses /reset/:token as a mountpath, and router is the nested router.

If you want router to be able to access req.params.token, create it as follows:

let router = express.Router({ mergeParams : true });

Documented here.

You are getting params and query mixed up.

Query approach

Your code should look like this when using query values for the example url: www.example.com?token=123&foo=bar

router.get('/', function(req, res, next) {
    console.log(req.query);
    console.log(req.query.token); // to log value of token
    console.log(req.query.foo);   // to log value of foo
    res.send(req.query);
});

Params approach

Your code should look like this when using params values for the example url: www.example.com/123

router.get('/:token', function(req, res, next) {
    console.log(req.params);
    console.log(req.params.token); // to log value of token
    res.send(req.params);
});

Instead you can use a middleware to log the path params:

const logger = (req, res, next)=>{
  console.log(req.params)
  res.send(req.params)
  next()//<----very important to call it.
};

app.use(logger); //<----use to apply in the app

router.get('/', (req, res, next)=>res.send('Logged.'));