JavaScript Prototypes

What are Prototypes?

Every object has a prototype. It's like a parent object that provides properties and methods.

┌─────────────────────┐
│   Object            │
│   ┌───────────────┐ │
│   │ name: "John"  │ │
│   └───────────────┘ │
│         │           │
│         │ __proto__ │
│         │           │
┌─────────▼───────────┐
│   Prototype         │
│   ┌───────────────┐ │
│   │ toString()    │ │
│   │ valueOf()     │ │
│   └───────────────┘ │
└─────────────────────┘

Prototype Chain

const arr = [1, 2, 3];

arr.push(4);  // Method from Array prototype
arr.toString(); // Method from Object prototype

JavaScript looks up the chain:

Array → Array.prototype → Object.prototype → null

Key Takeaway

Prototypes enable inheritance. Objects inherit from prototypes. Prototype chain allows method lookup. Understanding prototypes is key to advanced JavaScript.