What is the prototype chain in JavaScript?

Question

What is the prototype chain in JavaScript?

Answer

In JavaScript, inheritance happens through the prototype chain — every object has an internal [[Prototype]] link (accessible as __proto__).

When you access a property, JavaScript checks:

1. The object itself
2. Its prototype
3. The prototype’s prototype
   ... until it reaches Object.prototype

const parent = { greet: () => console.log('Hi!') };
const child = Object.create(parent);
child.greet(); // "Hi!"

If not found in the chain, it returns undefined.

Real-World Example

All arrays inherit from Array.prototype, which inherits from Object.prototype.

Quick Practice

Create two objects linked via prototype and access a property from the parent.

Summary

The prototype chain is JavaScript’s inheritance backbone — flexible, dynamic, and powerful.