Understanding Prototypes

In JavaScript, prototypes are the mechanism by which objects inherit features from one another. Every object has an internal property called [[Prototype]] (accessible via __proto__ or Object.getPrototypeOf()) that points to another object. When you try to access a property on an object and it does not exist, JavaScript looks up the prototype chain until it finds the property or reaches null.

Prototypes allow sharing methods and properties across instances, saving memory and enabling inheritance.

Code Example

// A simple object with a prototype
const animal = {
  eats: true,
  walk() {
    console.log("Animal walks");
  },
};

const rabbit = Object.create(animal); // rabbit's prototype is animal
rabbit.jumps = true;

console.log(rabbit.eats); // true (inherited from animal)
rabbit.walk(); // "Animal walks"