Nodejs Router require function but got an Object

Question

I am getting an error when calling my router from my routes directory whenever i try to initialize a route with app.use(). The error i am getting says Router.use() requires a middleware function but got an Object. I am not sure what exactly is wrong with my code below

Error:

C:\Users\Desktop\Projet\test\Todo\node_modules\express\lib\router\index.js:458 throw new TypeError('Router.use() requires a middleware function but got a ' + gettype(fn)) ^

TypeError: Router.use() requires a middleware function but got a Object at Function.use (C:\Users\Desktop\Projet\test\Todo\node_modules\express\lib\router\index.js:458:13) at Object. (C:\Users\Desktop\Projet\test\Todo\server\api\index.js:3:8) at Module._compile (module.js:652:30) at Object.Module._extensions..js (module.js:663:10) at Module.load (module.js:565:32) at tryModuleLoad (module.js:505:12) at Function.Module._load (module.js:497:3) at Module.require (module.js:596:17) at require (internal/module.js:11:18) at Object. (C:\Users\Desktop\Projet\test\Todo\server.js:23:13) at Module._compile (module.js:652:30) at Object.Module._extensions..js (module.js:663:10) at Module.load (module.js:565:32) at tryModuleLoad (module.js:505:12) at Function.Module._load (module.js:497:3) at Function.Module.runMain (module.js:693:10)

My server.js:

//Import dependencies

const express = require('express');
const path = require('path');
const http = require('http');
const bodyParser = require('body-parser');
const mongoose = require('mongoose');



//Connect to MongoDB server 

mongoose.connect('mongodb ://localhost/todoApp');
mongoose.set('debug',true);

//Import models

require('./server/models/Task');
require('./server/models/Todo');

//Get and Set API routes

const api = require('./server/api/');
app.use('/api',apiRoutes)

//Init express

const app = express();

//Enable bodyParser
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended:false}));

//Enable CORS

app.use(function(req,res,next){
    res.header("Access-Control-Allow-Origin","*");
    res.header("Access-Control-Allow-Methods","GET, POST ,DELETE, PUT");
    res.header("Access-Control-Allow-Headers","Origin, X-Requested-With, Content-Type, Accept, Authorization")
    next()
});

//Get env port 

const port = process.env.PORT || "3000";
app.set('port',port);

//Create HTTP server.

const server = http.createServer(app);

//Listen on port 

server.listen(port,() => console.log('Api running on localhost :${port}'));

and file where my controller's routes are:

var router = require('express').Router();

router.use('/todo',require('./todo'));
router.use('/todo/task',require('./task'));



module.exports = router ; 

todo file :

const router = require('express').Router();
const mongoose = require('mongoose');

const Todo = mongoose.model('Todo');
const Task = mongoose.model('Task');

router.param('todo', function (req, res, next, id) {
    if (!id.match(/^[0-9a-fA-F]{24}$/)) {
        return res.sendStatus(422);
    }

    Todo.findById(id)
        .populate('tasks')
        .then(function (todo) {
            if (!todo) { return res.sendStatus(404); }

            req.todo = todo;

            return next();
        });
 });

 router.get('/',(req,res)=>{
     Todo.find()
        .populate('tasks')
        .then((todos)=>{
            if (!todos){return res.sendStatus(404);}

            return res.json({
                todos:todos.map((todo)=>{
                    return todo.toDto();
                })
            }).statusCode(200);
        });
 });

 router.post('/', (req, res) => {
    if (!req.body.title) {
        res.sendStatus(422);
    }

    let todo = new Todo();
    todo.title = req.body.title;

    todo.save().then(() => {
        res.json(todo.toDto()).statusCode(201);
    })

 });

 router.delete('/:todo', (req, res) => {

    req.todo.remove().then(function () {
        return res.sendStatus(200);
    });
 });

Task file :

const router = require('express').Router();
const mongoose = require('mongoose');

const Todo = mongoose.model('Todo');
const Task = mongoose.model('Task');


router.param('task',function(req,res,next,id){
    if(!id.match(/^[0-9a-fA-F]{24}$/)){
        return res.sendStatus(422);
    }
    Task.findById(id).then ((task) =>{
        if(!task){return res.sendStatus(404);}
        req.task = task;

        return next();
    })
})

router.post('/', (req, res) => {
    if (!req.body.todoId || !req.body.content) {
        res.sendStatus(422);
    }

    if (!req.body.todoId.match(/^[0-9a-fA-F]{24}$/)) {
        res.sendStatus(422);
    }

    Todo.findById(req.body.todoId).then((todo) => {
        if (!todo) { res.statusCode(404); }

        let task = new Task();
        task.content = req.body.content;
        task.state = false;
        task.todo = todo;

        task.save().then(() => {

            todo.tasks.push(task);

            todo.save().then(() => {
                res.json(task.toDto()).statusCode(201);
            });
        });
    });
 });

 router.put('/', (req, res) => {

    if (req.body.state == undefined || !req.body.id) {
        res.sendStatus(422);
    }

    if (!req.body.id.match(/^[0-9a-fA-F]{24}$/)) {
        res.sendStatus(422);
    }


    Task.findById(req.body.id).then((task) => {
        task.state = req.body.state;

        task.save().then(() => {
            res.json(task.toDto()).statusCode(200);
        });
    });
 });

 router.delete('/:task', (req, res) => {
    let task = req.task;

    task.remove().then(() => {
        res.sendStatus(200);
    });
 });

Answer 1

//Init express
const app = express();

//Get and Set API routes

const api = require('./server/api/');
app.use('/api',apiRoutes)

Change apiRoutes to api. apiRoutes is not defined
Initialize express before setting router.