index.js

import express from 'express';
import mongoose from 'mongoose';
import router from './routes/problems.js';

try {
    const app = express();
    await mongoose.connect(`mongodb://127.0.0.1:27017/${process.env.DB_NAME}`, {
        serverSelectionTimeoutMS: 3000
    });

    //Middleware to support application/json
    app.use(express.json());

    //Middleware to support
    app.use(express.urlencoded({extended: true}));

    app.use((req, res, next) => {
        // Block non accept: application/json requests
        if (req.header('Accept') !== 'application/json' && req.method !== 'OPTIONS'){
            res.status(406);
            res.json({error: 'only JSON is allowed as Accept header (Math Problems API)'});
            return;
        }

        next();
    });

    app.get('/', (req, res) => {
        res.json({message: 'Welcome to my webservice for math problems!'});
    });

    app.use('/problems', router);

    app.listen(process.env.EXPRESS_PORT, () => {
        console.log('Server has started');
    });

} catch (e) {
    console.log('e');
};