Understanding the two faces of inheritance in JavaScript — syntax sugar vs raw mechanics, and which one you should use today.

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Introduction

If you’ve been coding in JavaScript for a while, you’ve probably seen both styles:

// Prototype-based
function Animal(name) {
  this.name = name;
}
Animal.prototype.speak = function() {
  console.log(this.name + " makes a sound.");
};

// ES6 Class
class Dog extends Animal {
  speak() {
    console.log(this.name + " barks.");
  }
}

So… which is better? The “classic” prototype-based inheritance or the newer ES6 class syntax? The truth: they’re the same engine under the hood. The difference is mostly developer experience, readability, and safety.

This article dives into:

• How prototypes and classes really work.
• The pros and cons of each.
• Real-world use cases (React, Node, libraries).
• Performance considerations.
• A clear answer: which one wins in modern code.

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1. JavaScript Inheritance Recap

• Every object has a hidden [[Prototype]] (its parent object).
• Functions have a .prototype property, which becomes the [[Prototype]] of objects created with new.
• When you call a property/method on an object, JS looks up the prototype chain until it finds it (or hits null).

Classes? Just a cleaner way to wire up these links.

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2. Prototypes — The Raw Mechanism

Before ES6, inheritance was done with constructor functions and prototypes.

function Animal(name) {
  this.name = name;
}
Animal.prototype.speak = function() {
  console.log(this.name + " makes a sound.");
};

function Dog(name) {
  Animal.call(this, name); // inherit props
}
Dog.prototype = Object.create(Animal.prototype); // inherit methods
Dog.prototype.constructor = Dog; // fix constructor reference
Dog.prototype.speak = function() {
  console.log(this.name + " barks.");
};

const rex = new Dog("Rex");
rex.speak(); // Rex barks.

Pros:

• Explicit: you see exactly how prototypes are wired.
• Flexible: you can modify prototypes at runtime.

Cons:

• Verbose (boilerplate Object.create, constructor fix).
• Easy to make mistakes (forgetting .call(this), messing up chains).
• Harder for newcomers to read.

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3. ES6 Classes — The Sugar Layer

ES6 introduced class as syntactic sugar:

class Animal {
  constructor(name) {
    this.name = name;
  }
  speak() {
    console.log(this.name + " makes a sound.");
  }
}

class Dog extends Animal {
  speak() {
    console.log(this.name + " barks.");
  }
}

const rex = new Dog("Rex");
rex.speak(); // Rex barks.

Under the hood:

• class Dog extends Animal sets Dog.prototype.__proto__ = Animal.prototype.
• constructor is just a function.
• methods go on .prototype.

Pros:

• Cleaner, more readable.
• Built-in extends and super.
• Consistent semantics across JS engines.
• Familiar to devs from Java, C#, etc.

Cons:

• Still “just sugar” — you need to know prototypes to debug deeply.
• Less flexible than raw prototypes (e.g., dynamic modification discouraged).
• Can create an illusion that JS has “classical OOP” (it doesn’t).

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4. Comparing Features

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5. Real-World Use Cases

Frameworks & Libraries

• React components:
   Early React used createClass (prototype-based). Modern React uses class components (extends React.Component) and, even more, functional components.
• Node.js Core:
   Many modules (e.g., EventEmitter) are built with prototypes. ES6 classes wrap or extend them in userland.

Prototypal Inheritance as a Feature

Sometimes, raw Object.create inheritance is simpler:

const animal = { eats: true };
const dog = Object.create(animal);
dog.barks = true;
console.log(dog.eats); // true

No classes, no constructors — just objects linked together.

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6. Performance Considerations

Modern JS engines (V8, SpiderMonkey, etc.) optimize both classes and prototypes. The performance difference is negligible for 99% of apps.

Where it matters:

• Hot loops with object creation.
• Libraries defining thousands of tiny objects.

👉 In practice: choose readability, not micro-optimizations.

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7. Common Gotchas

this Binding

class Dog {
  speak() { console.log(this.name); }
}
const f = new Dog("Rex").speak;
f(); // ❌ undefined (lost `this`)

Fix with .bind or arrow functions.

Static Methods

class Animal {
  static create(name) {
    return new Animal(name);
  }
}
const a = Animal.create("Zoe"); // works

Prototype Pollution

Messing with built-in prototypes (Array.prototype, Object.prototype) is dangerous — it affects all objects.

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8. So… Who Wins?

1. Use ES6 Classes for:

• Readable, structured inheritance.
• Framework integration (React, Angular, TypeScript).
• Team projects where clarity matters.

2. Use Prototypes directly for:

• Lightweight object delegation (Object.create).
• Polyfills and library internals.
• Advanced meta-programming where classes feel restrictive.

👉 Verdict (2025): ES6 Classes win for almost all modern code. Prototypes are still essential knowledge, but you’ll rarely write raw prototype chains outside of experiments or deep library internals.

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Conclusion

JavaScript’s inheritance model is prototype-based at its core. ES6 classes don’t change that — they just give us cleaner, more familiar syntax.

Key takeaways:

• Classes = sugar, prototypes = engine.
• Learn prototypes to understand, use classes to write.
• Favor immutability, composition, and functions where possible — inheritance isn’t always the best tool.

Pro tip: If debugging weird inheritance, crack open the chain:

console.log(Object.getPrototypeOf(obj));

It’ll remind you what’s really going on.

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Call to Action

Have you ever run into a bug because you didn’t understand prototypes behind classes?

💬 Share your story in the comments.
🔖 Bookmark this for your next interview prep.
👩‍💻 Send it to a teammate who still thinks ES6 classes replaced prototypes.