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

• It is a class that allows only a single instance of itself to be created and gives access to that created instance

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

• A singleton represents a single instance of an object. Only one can be created, no matter how many times the object is instantiated. If there’s already an instance, the singleton will create a new one.

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

• use Singleton to prevent other objects from instantiating their own copies of the Singleton object, ensuring that all objects access the single instance

Document the following Vocabulary Terms

• Router Middleware: a piece of code that comes in the middle of request and response

• Dynamic Module Loading: a mechanism by which a computer program can, at run time, load a library (or other binary) into memory

• Singleton Pattern: it restricts the instantiation of a class to one single instance

• CRUD -> REST Method Matches

  • create–POST
  • read–GET
  • update–PUT
  • delete–DELETE

• Mock Testing

  • creating a fake version of an external or internal service that can stand in for the real one, helping your tests run more quickly and more reliably

Resouces

• Singleton

• Singleton Patterns

• Mock Testing

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