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Explain what a “Singleton” is (in Computer Science terms)

https://betterprogramming.pub/what-is-a-singleton-2dc38ca08e92

• restricts the instantiation of a class to a single instance.
• provides coordinated access to a single resource
• considered an alternative to global variables

Explain how the Singleton pattern can be used with Node modules, specifically with classes

If you were tasked with building a middleware system like Express uses, what approach might you take to construct/operate it?

http://expressjs.com/en/guide/using-middleware.html

Middleware functions can perform the following tasks:

• Execute any code.
• Make changes to the request and - the response objects.
• End the request-response cycle.
• Call the next middleware function in the stack.

Router Middleware

http://expressjs.com/en/guide/using-middleware.html#middleware.router

Router-level middleware works in the same way as application-level middleware, except it is bound to an instance of express.Router().

var router = express.Router()

Dynamic Module Loading

https://dev.to/hasnaindev/dynamic-module-pattern-for-javascript-dynamically-load-javascript-bundles-m5c

• you define in markup what JS should be loaded

Singleton Pattern

• A creational design pattern that restricts the instantiation of a class to one object.

CRUD -> REST Method Matches

Create = PUT with a new URI POST to a base URI returning a newly created URI Read = GET Update = PUT with an existing URI Delete = DELETE

Mock Testing

• building test files to automatically run or use thunderclients