How to connect to MongoDB using Node.js written in TypeScript?

I'm working on a Node.js server, connecting to MongoDB and written with TypeScript. When I try to use MongoDB it doesn't create a connection, however when I check the mongo output it does appear to create a connection.

What am I missing in my code to define the connection in Node.js?

My connection method:

connect() {
    console.log('connecting to mongo') //this is called
    MongoClient.connect(this.connectionString, {useNewUrlParser: true})
    .then(client => {
        console.log('setting client'); //this doesn't get called
        this.client = client;
        console.log(this.client);
    })
    .catch(error => {
        console.log('error during connecting to mongo: '); //this also doesn't get called
        console.error(error);
    });
}

Mongo output:

2018-11-08T23:06:24.106+0100 I NETWORK [listener] connection accepted from 127.0.0.1:51345 #11 (2 connections now open)

2018-11-08T23:06:24.107+0100 I NETWORK [conn11] received client metadata from 127.0.0.1:51345 conn11: { driver: { name: "nodejs", version: "3.1.9" }, os: { type: "Darwin", name: "darwin", architecture: "x64", version: "17.7.0" }, platform: "Node.js v8.9.3, LE, mongodb-core: 3.1.8" }

My repository is at https://github.com/FrisoDenijs/MEAN-ToDo/blob/master/server/src/db/mongo.db.ts for the full code.

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