user auth in express

index.js

app.use(async (req, res, next)=>{
  try {
    req.user = await auth.validate(req);
  } catch(err) {
    if (...)
        return res.json({error: 'user not found'});
    next(err);
  }
});

app.get('/test', (req, res)=>{
  res.json(req.user);
});