Password Generator

A NodeJS-API to generate passwords based on user input.

General description and some thoughts on the process:

The challenge was to create an api that receives user input (min length, number of special chars, number of numbers and number of passwords to generate). Based on the fact, that user data is submitted, the endpoint is designed as post request as would be anticipated while processing form data (user input). It could have been realized as a plain get-Request with either parameterized url:
Schema: /password/v1/generate/:min/:specialChars/:numbers/:passwords
Call: /password/v1/generate/10/3/3/10
or with an url followed by a query string:
Schema: /password/v1/generate
Call: /password/v1/generate?min=10&specialChars=3&numbers=3&passwords=10
Security concerns are for all three approaches the same if not been used via https, therefore no method has a real advantage over the other. The one thing that made the decision point towards using post was that post has the least side effects while dealing with form data.

Above that the API has literally two endpoints supplying the same results but with different approaches behind the scenes: the v1-Route utilises a functional approach on the controller side, whereas the v2-Route utilises a class-based approach.
At this point no further decision was made just because to walk through the process of implementing both ways.

After implementing both ways, the functional approach has one advantage over the other: no this-problem This leaves aside the somehow wired implementation of this in JavaScript/TypeScript one has to deal with while using classes. Apart from the this-problem, it is a mere decision of style and preference.

Another difference between class and functional approach is the handling of potential errors with the submitted data. Using typed params does not fully guarantee that there will be no errors. However the functional approach checks for NaN after trying to parse the submitted data to numbers, whereas the class-based approach checks for valid typing at usage during the actual generation loop. A submitted nonnumerical string is stored in a variable of type number without initial complain. That is because types are only checked during compile time and not at run time.

Documentation:

Libraries used:

Production

Package Name	Use case
express	server framework
helmet	security middleware collection
cors	enable cross-origin resource sharing
morgan	route logging middleware

Development

Package name	Use case
jest	test framework
ts-jest	tool to enable testing typescript
nodemon	tool to rerun the dev server during development to map changes in the code
ts-node	enable nodemon to run typescript files

Beside of the listed external dependencies, the node crypto library was used to generate random numbers.

Server:

The server listens to port 8000 per default but the port can be changed via environment variable

Commands:

npm test runs the test suites
npm run start:dev spawns a nodemon process to run the dev server
npm run start:debug spawns a nodemon process with debug settings
npm run start:build compiles the app and run the compiled script.

Endpoints:

password/v1/generate
password/v2/generate