Theoretical Foundations of Object-Oriented Programming in JavaScript

Object-Oriented Programming (OOP) is a programming paradigm designed to model real-world concepts using objects, classes, inheritance, and methods. It promotes organization, reusability, and extensibility of code.

JavaScript is not inherently a "class-based" language; it is a prototype-based language, meaning inheritance is based on the [[Prototype]] linkage rather than actual classes. However, the class syntax added since ES6 is merely a layer to emphasize class-like imitation.

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Why is OOP Important in Software Architecture?

As the scale of programs grows, it becomes necessary to divide code into smaller modules, hide complexities, and reduce dependencies. This is where OOP shines by offering the following capabilities:

• Modularity — Code is divided into modules via classes or objects.
• Encapsulation — Data and functions are kept in one place and are not accessible from the outside without necessity.
• Reusability — Inheritance and composition allow the same structure to be reused multiple times.
• Scalability — OOP structure makes it easier to extend applications without breaking existing logic.

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JavaScript's Unique Features in the Context of OOP

Unlike Java or C++, classes in JavaScript are not a foundational part of the language. They are pseudo-classes built on top of the Object and Function types in the browser. For example, when you create a class, the browser creates a constructor function where methods are placed in its prototype.

class User { constructor(name) { this.name = name; }
greet() { console.log(Hello, ${this.name}); } }

const u = new User('Ani'); u.greet(); // Hello, Ani

But in reality, this is what the engine understands:

function User(name) { this.name = name; }
User.prototype.greet = function() { console.log(Hello, ${this.name}); };

This is JavaScript's underlying prototype chain—not real classes.

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Paradigm Comparison: Procedural vs OOP vs Functional

Paradigm	Core Idea	Code Organization
Procedural	Commands, procedures	Functions + global data
OOP	Objects, classes,	Objects and methods
Functional	Pure functions, data immutability	Composability + referential transparency

JavaScript is unique in that it supports all three, allowing the programmer to choose the most suitable approach for a given problem.

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Conclusion

OOP in JavaScript provides structural thinking, especially when designing large systems. However, it's important to understand that the class syntax is merely syntactic sugar layered on top of the prototype model. The real power of OOP comes from the correct application of its principles, not just the use of classes.

In the next part, we will discuss different methods of object construction, from the most fundamental to the most flexible approaches.

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