Welcome to itzibitzi.js

Try it now https://einar.io/code/MongoDB-Coding-Challenge.JS

Based on my previous experience with implementing a solution in Haskell, I decided to reimplement the challenge in JavaScript, because I concluded that would have a better tool for the job all along. To improve the approachability of the code, I thought I would implement a tiny web interface as well.
I took the opportunity to upgrade my VPS to Nginx. The web interface is available right now on my homepage.

Command-line interface

I am going to assume you have already installed node.js and npm on your system. Then run:

git clone git@github.com:einar-io/MongoDB-Coding-Challenge.JS.git
cd MongoDB-Coding-Challenge.JS
npm start

Test suite

The tests can be run with

npm test

There are currently 11 unit tests.

Steps

The steps taken were as follows:

1. Set up node.js project.
2. Create simple echo service as CLI.
3. Implement the evaluator function for flatten.
4. Create web interface.
5. Migrate web server form Apache2 to Nginx.
6. Port the tests from Haskell to jest.

I consider implementing the following features:

7. Add async/await to itzibitzi.js.
8. Dockerize the app and set up nginx as a reverse proxy.
9. Add CSS and improve the presentation of the web interface.
10. Add type annotations for TypeScript.
11. Add continuous integration and automatic deployment.

Takeaways

1. Unfortunately I did not manage to make a black-box testing of the cli.js. Either I need to understand Jest better, or there is a bug somewhere. The manual tests conducted did not reveal any problems.

2. Jest's integration with ES6 modules seemed to be unreliable, so I went with CommonJS after some headaches.

3. JavaScript is not known for its consistent type system. This time around I learnt that:

    typeof null === Object
    null instanceof Object === false
   

Thank you for reading!

Do not hesitate to contact me if you have questions or need advice on how to use my solution.

Kind regards

Einar Rasmussen einar@einar.io LinkedIn