[javascript] TypeError: Router.use() requires middleware function but got a Object

There have been some middleware changes on the new version of express and I have made some changes in my code around some of the other posts on this issue but I can't get anything to stick.

We had it working before hand but I can't remember what the change was.

throw new TypeError('Router.use() requires middleware function but got a
        ^
TypeError: Router.use() requires middleware function but got a Object

node ./bin/www

js-bson: Failed to load c++ bson extension, using pure JS version
js-bson: Failed to load c++ bson extension, using pure JS version

/Users/datis/Documents/bb-dashboard/node_modules/express/lib/router/index.js:438
      throw new TypeError('Router.use() requires middleware function but got a
            ^
TypeError: Router.use() requires middleware function but got a Object
    at /Users/datis/Documents/bb-dashboard/node_modules/express/lib/router/index.js:438:13
    at Array.forEach (native)
    at Function.use (/Users/datis/Documents/bb-dashboard/node_modules/express/lib/router/index.js:436:13)
    at /Users/datis/Documents/bb-dashboard/node_modules/express/lib/application.js:188:21
    at Array.forEach (native)
    at Function.use (/Users/datis/Documents/bb-dashboard/node_modules/express/lib/application.js:185:7)
    at Object.<anonymous> (/Users/datis/Documents/bb-dashboard/app.js:46:5)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)

app.js

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var session = require('express-session');
var MongoClient = require('mongodb').MongoClient;
var routes = require('./routes/index');
var users = require('./routes/users');

var Users = require('./models/user');
var Items = require('./models/item');
var Store = require('./models/store');
var StoreItem = require('./models/storeitem');

var app = express();
//set mongo db connection
var db = mongoose.connection; 

MongoClient.connect("mongodb://localhost:27017/test", function(err, db) {
  if(!err) {
    console.log("We are connected");
  }
});
// var MONGOHQ_URL="mongodb://localhost:27017/test" 

// view engine setup
app.set('views', path.join(__dirname, 'views'));

app.set('view engine', 'ejs');

// uncomment after placing your favicon in /public
//app.use(favicon(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(session({
    secret: 'something',
    resave: true,
    saveUninitialized: true
}));

app.use('/', routes);
app.use('/users', users);
app.use(express.static(path.join(__dirname, 'public')));

// catch 404 and forward to error handler
// app.use(function(req, res, next) {
//     var err = new Error('Not Found');
//     err.status = 404;
//     next(err);
// });

// Make our db accessible to our router
app.use(function(req, res, next){
  req.db = db;
  next();
});

// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function(err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});


module.exports = app;

It appears the answer to this question has changed for versioning reasons. Thanks to Nik

Simple solution if your are using express and doing

const router = express.Router();

make sure to

module.exports = router ;

at the end of your page

I was getting the same error message but had a different issue. Posting for others that are stuck on same.

I ported the get, post, put, delete functions to new router file while refactoring, and forgot to edit the paths. Example:

Incorrect:

//server.js
app.use('/blog-posts', blogPostsRouter);

//routers/blogPostsRouter.js
router.get('/blog-posts', (req, res) => {
  res.json(BlogPosts.get());
});

Correct:

//server.js
app.use('/blog-posts', blogPostsRouter);

//routers/blogPostsRouter.js
router.get('/', (req, res) => {
  res.json(BlogPosts.get());
});

Took a while to spot, as the error had me checking syntax where I might have been wrapping an argument in an object or where I missed the module.exports = router;

In any one of your js pages you are missing

module.exports = router;

Check and verify all your JS pages

You are missing router exports module and that is the reason why this error is present.

use module.exports = router; and that would work

Check your all these file:

var users = require('./routes/users');

var Users = require('./models/user');
var Items = require('./models/item');

Save properly, In my case, one file was missed and throwing the same error

check your routes.js file

example my routes.js

    const express = require('express')_x000D_
    const router = express.Router()_x000D_
    _x000D_
    const usersController = require('../app/controllers/usersController')_x000D_
    const autheticateuser = require('../app/middlewares/authentication')_x000D_
    _x000D_
    router.post('/users/login', autheticateuser, usersController.login)_x000D_
    router.post('/users/register', autheticateuser, usersController.register)_x000D_
      

check end of routes.js

module.exports = router

if not there add and module.exports = router run again

If your Error is : "TypeError: Route.post() or Route.get() requires middleware function but got a Object"

goto controller.js (i.e., usersController) and check all the function names you might misspelled , or you given in function routes file but missed in contollers

const User = require('../models/user')_x000D_
const express = require('express')_x000D_
const router = express.Router()_x000D_
_x000D_
_x000D_
_x000D_
module.exports.register = (req, res) => {_x000D_
    const data = req.body_x000D_
    const user = new User(data)_x000D_
    user.save()_x000D_
        .then((user) => {_x000D_
            res.send(user)_x000D_
        })_x000D_
        .catch((err) => {_x000D_
            res.json(err)_x000D_
        })_x000D_
}

in routes.js i given two routes but in controllers i missed to define route for

router.post('/users/login')

this will make error **

"TypeError: route.post() requires middleware function but got a Object"

**

In my case i wasn't exporting the module. module.exports = router;

I had this error and solution help which was posted by Anirudh. I built a template for express routing and forgot about this nuance - glad it was an easy fix.

I wanted to give a little clarification to his answer on where to put this code by explaining my file structure.

My typical file structure is as follows:

/lib

/routes

---index.js (controls the main navigation)

/page-one



/page-two



     ---index.js

(each file [in my case the index.js within page-two, although page-one would have an index.js too]- for each page - that uses app.METHOD or router.METHOD needs to have module.exports = router; at the end)

If someone wants I will post a link to github template that implements express routing using best practices. let me know

Thanks Anirudh!!! for the great answer.