Wiring Modules: Singleton Dependencies
Explore how to manage dependencies in Node.js applications by implementing the Singleton design pattern. This lesson shows you how to create and use singleton modules, such as a database connection, and discusses the benefits and limitations of this approach in development and testing scenarios.
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Wiring modules
Every application is the result of the aggregation of several components and, as the application grows, the way we connect these components becomes a win or lose factor for the maintainability and success of the project.
When a component, A, needs component B to fulfill a given functionality, we say that “A is dependent on B” or, conversely, that “B is a dependency of A.” To appreciate this concept, let’s look at an example.
Let’s say we want to write an API for a blogging system that uses a database to store its data. We can have a generic module implementing a database connection (db.js) and a blog module that exposes the main functionality to create and retrieve blog posts from the database (blog.js).
The following figure illustrates the relationship between the database module and the blog module:
In this section, we’re going to see ...