Prototypal vs Classical Inheritance

Prototypal vs Classical Inheritance

Classical Inheritance (Java, C++)

• Classes: blueprints for objects. Objects are instances of classes.
• Hierarchy: classes inherit from other classes.
• Strict: defined at compile time. Cannot change at runtime.
• Multiple inheritance: some languages support it (C++), some do not (Java).

Prototypal Inheritance (JavaScript)

• Objects: objects inherit directly from other objects. No classes (ES6 classes are sugar).
• Chain: objects link to other objects via the prototype chain.
• Dynamic: prototypes can be changed at runtime.
• Single inheritance: each object has one prototype (but can compose).

Key Differences

Composition Over Inheritance

In JavaScript, composition (mixing objects) is often preferred over deep inheritance chains:

const canFly = { fly: () => "flying" };
const canSwim = { swim: () => "swimming" };
Object.assign(bird, canFly);
Object.assign(fish, canSwim);

The Takeaway

Classical: classes inherit from classes (static, strict). Prototypal: objects inherit from objects (dynamic, flexible). JS uses prototypal. ES6 classes are syntactic sugar. Prefer composition over deep inheritance chains.