I've made a blog page with a sign up and sign in. So I had used the req.locals.<name> method
With the GET method.

Code in server.js

app.get('*',(req,res, next) => {
  res.locals.user = req.user || null;
  next();
})

And I used the user variable in a pug page's navbar like :-

nav.navbar.navbar-expand-lg.navbar-light.bg-light
  .container
    a.navbar-brand.text-center.me-2(href='/') IA INFO
    button.navbar-toggler(type='button' data-bs-toggle='collapse' data-bs-target='#navbarSupportedContent' aria-controls='navbarSupportedContent' aria-expanded='false' aria-label='Toggle navigation')
      span.navbar-toggler-icon
    #navbarSupportedContent.collapse.navbar-collapse.justify-content-end
      ul.nav.nav-tabs
        li.nav-item
          a.nav-link(aria-current='page' href='/') Home
        li.nav-item
          a.nav-link(href='/blogs') Blogs
        if user
            li.nav-item
                a.nav-link(href='/blogs/add/new-blog') New Blog
            li.nav-item
                a.nav-link(href='/blogs/admin/sign') Sign
            li.nav-item
                a.nav-link(href='/logout') Logout

But when i try this method it doesn't really work....
After anyone logs-in, it is supposed to work but then it shows me an error of user is not defined or it just doesnt work...