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It is possible to pass control back to the next middleware function or route method outside of a router by calling next('router').

router.use((request, response, next) => { 
  next('route') 
}) 

For example, by creating a router that expects to receive a user ID as a query parameter. The next('router') function can be used to get out of the router or pass control to the next middleware function outside of the router when a user ID is not provided. The next middleware function out of the router can be used to display other information when the router passes control to it. For example:

1. Create a new file named router-level-control.js
2. Initialize a new ExpressJS application:

      const express = require('express') 
      const app = express() 

1. Define a new router:

      const router = express.Router() 

1. Define our logger middleware function inside the router:

      router.use((request, response, next) => { 
         if (!request.query.id) { 
             next('router') // Next, out of Router 
          } else { 
            next() // Next, in Router 
          } 
      }) 

1. Add a route method to handle GET requests for path "/" which will be executed only if the middleware function passes control to it:

       router.get('/', (request, response, next) => { 
         const id = request.query.id 
         response.send(`You specified a user ID => ${id}`) 
      }) 

1. Add a route method to handle GET requests for path "/" outside of the router. However, include the router as a route handler as the second argument, and another route handler to handle the same request only if the router passes control to it:

      app.get('/', router, (request, response, next) => { 
          response 
            .status(400) 
            .send('A user ID needs to be specified') 
    }) 

1. Listen on port 1337 for new connections:

      app.listen( 
          1337, 
          () => console.log('Web Server running on port 1337'), 
      ) 

1. Save the file
2. Open a terminal and run:

      node router-level-control.js

1. To see the result, in your browser, navigate to:

  http://localhost:1337/
      http://localhost:1337/?id=7331