TypeError: is not a constructor with Node and Express JS

Question

I wrote code below and I have a TypeError: Server is not a constructor and I don't see why and how to fixe it.

Server.js code :

const express = require('express');

class Server {
    constructor() {
        this.app = express();

        this.app.get('/', function(req, res) {
            res.send('Hello World');
        })
    }

    start() {
        this.app.listen(8080, function() {
            console.log('MPS application is listening on port 8080 !')
        });
    }
}

app.js code :

const Server = require('./Server');
const express = require('express');

const server = new Server();

server.start();

did you export the Server from Server.js? what does app.js say when you ask it to console.log(Server) — Krzysztof Krzeszewski
– Krzysztof Krzeszewski, Commented Nov 15, 2019 at 8:07
add module.exports = Server at the end of your Server.js code — BadPiggie
– BadPiggie, Commented Nov 15, 2019 at 8:08
Thanks @Krzysztof Krzeszewski and @ Banujan Balendrakumar it was that ! — MissKnacki
– MissKnacki, Commented Nov 15, 2019 at 8:09

SteapStepper69 · Accepted Answer · 2019-11-15 08:09:33Z

5

You did not export the Server class. In your 'Server.js' file, do this:

export default Server {
...
}

and leave your 'app.js' like this:

const Server = require("./Server");

The above method only works with ES6 and up, if not using ES6:

class Server {
...
}

module.exports = Server;

answered Nov 15, 2019 at 8:09

SteapStepper69

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BadPiggie · Accepted Answer · 2019-11-15 08:09:56Z

2

You need to export your class before import anywhere,

Add the following line at the end of your Server.js

module.exports = Server

ES6

export default Server {
 // you implementation
}

answered Nov 15, 2019 at 8:09

BadPiggie

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