How to build a Node.js project? & How to organize Node.js code?

Node.js Project and Modular Architecture

Node.js, cross-platform JavaScript runtime environment, executes code outside of a browser. Its basic module loading method considers each file as a module. Creating loosely linked, complicated applications requires modules to encapsulate related code.

Working on the same codebase with different team members requires a well-organised project structure. Common patterns divide concerns for greater manageability, although personal preferences and project architecture might influence structure.

Web applications using Express.js commonly use the Model-View-Controller (MVC) structure. This usually contains functionally specific directories for code:

1. Models: Especially when utilising Mongoose to integrate with databases such as MongoDB, models are essential because they include the schema definition for data.
2. Routes: Specify the controllers and map the API routes. Express simplifies organisation by enabling the creation of distinct routers that can be integrated into a single application.
3. Controllers: Controllers are in charge of processing queries, validating request parameters, and returning answers with the proper HTTP codes.
4. Services: Usually include business logic and database queries that provide the controllers with errors or objects.

A simple Node.js application with an MVC and API structure, especially when built using Browserify and a frontend framework, may distinguish between server-side (backend) and client-side (frontend) modules.

The overall project structure could look something like this:

|-- node_modules
|-- src
|    |-- server             // Backend modules
|    |    |-- controller
|    |    |-- dto           // Data Transfer Objects
|    |    |-- App.js        // Main Node app entry point
|    |-- webapp             // Frontend modules
|    |    |-- public        // Static resources (images, CSS, HTML, minified scripts)
|    |    |    |-- build
|    |    |    |-- images
|    |    |    |-- styles
|    |    |    |-- views
|    |    |    |-- index.html
|    |    |-- mvc           // Frontend logic (models, view controllers, utils)
|    |    |    |-- controllers
|    |    |    |-- utils
|    |    |    |-- index.js  // MVC shell
|-- config                  // Environment and business logic configurations
|-- Readme.md
|-- .gitignore
|-- package.json

Inside this framework:

• App.js (or index.js) within the server directory serves as the main Node.js file and starting point.
• The dto directory holds data transfer objects used by API controllers.
• The webapp directory is divided into public for static resources (images, CSS, HTML, minified scripts) and mvc for frontend logic.
• package.json contains metadata about the project and lists dependencies.

Because related code is organised together thanks to this modular approach, the codebase is easier for new developers to comprehend and more readable. Because npm provides numerous modules for common functionality like file system operations and HTTP servers, it also facilitates code reuse by avoiding the need for developers to redo these activities.

Coding Best Practices

Implementing sound coding techniques improves Node.js apps’ quality, maintainability, and debuggability.

1. Aim for Shallow Code: Node.js’ asynchronous nature and constant use of callbacks make shallow code crucial. Nested callback functions, known as “Callback Hell” or “The Pyramid of Doom”, can render code illegible. There should be no more than two callback functions nestled together to prevent this. Asynchronous code flow can be simplified with async.js, Promises, and async/await syntax, decreasing nesting and enhancing readability. For instance, async/await lets asynchronous code look like synchronous code and be easier to maintain.
2. Using Common Contexts for Callbacks: Node.js API callback functions receive two parameters: err (for errors) and data (for outcomes). Reducing indentation by stopping execution in the if block and handling the problem (e.g., by logging or throwing it) are both excellent practices. When using ES6 features, arrow functions are beneficial because they do not bind their own this value, instead inheriting this from the enclosing lexical context. This avoids common this binding issues in callback-heavy code.
3. Naming Functions Clearly: While debugging, a stack trace with unique function names is easier to read and understand.
4. Don’t Repeat Yourself (DRY) Principle: If you continually copy and paste the same code, extract it into a reusable function. To log note details, for instance, a function might be made and used to various commands:
5. Original code that was repeated, such as the add and read commands:
6. Making use of a logNote function to apply DRY:
7. If it becomes necessary to modify the logging format, this refactoring avoids inconsistencies and makes the code more manageable and simple.
8. Error Handling: Try…catch blocks for synchronous code and managing faults sent to callbacks for asynchronous operations are two examples of techniques for error management that Node.js offers.

Through the implementation of these principles and careful Node.js application structure, you may create systems that are reliable, effective, and readily expandable.