matfin / geo-customers

An exercise in Typescript

What is this?

This is a small exercise I put together in Typescript.

It fetches a list of users from an endpoint and displays them in a sorted manner. It makes use of the formulae outlined in this Wikipedia article to calculate which users fall within a particular distance from a place.

This exercise was put together as a simple demonstration of a NodeJS command line app with full test coverage and a basic tool chain for Javascript developers.

How do I run it?

First, you need to have NodeJS installed. Once this is set up, follow these instructions:

1. Clone this repository to your local machine

• you$: git clone [e-mail]:matfin/geo-customers.git

2. Install the dependencies

• you$: npm install

3. Run the application to display a list of fetched users sorted by their user ID in ascending order

• you$: npm start
• you$: npm start > output.txt if you want to write to a file
• you$: DISTANCE_KM=30 npm run start if you want to use environment variables to override values (see below)

4. Environment variables The following environment variables when set, will override the default values:

• BASE_URL
• LAT
• LNG
• DISTANCE_KM

Code quality

This is covered too, so if you want run tests and see tests and coverage, run:

• you$: npm run test
• you$: npm run coverage

Code quality checks are carried out with ESLint, so run:

• you$: npm run lint

What is missing?

I could have wrapped this in a nice UI - maybe creating a cool app with the latest framework, visualsing users on a Google map with individual icons for each one of them relative to the office.

I wanted to take a pragmatic approach to this problem and stick to the script as much as possible. I have a working solution full test coverage and code lint checkers making sure everything is ok.

Separation of concerns has also been dealt with. A function to fetch users, for instance, should only be concerned with fetching a list of users. We can use something else to deal with filtering and sorting.