Prototypes
Prototypes
Section titled “Prototypes”Introduction
Section titled “Introduction”Every JavaScript object has a prototype — an internal reference to another object from which it inherits properties. This is JavaScript’s mechanism for prototypal inheritance.
Learning Objectives
Section titled “Learning Objectives”- Understand the prototype chain and how property lookup works
- Learn how to set and get prototypes
- Master
Object.create()for prototypal inheritance - Understand built-in prototypes (Array.prototype, etc.)
- Know when to use prototypes vs instance properties
Visual Summary
Section titled “Visual Summary”flowchart TD A["myArray: [1, 2, 3]"] B["Array.prototype: push, pop, map..."] C["Object.prototype: toString, hasOwnProperty..."] D["null"]
A -->|"[[Prototype]]"| B B -->|"[[Prototype]]"| C C -->|"[[Prototype]]"| DTopics Covered
Section titled “Topics Covered”| Topic | Description | Est. Time |
|---|---|---|
| Prototype Chain | How property lookup traverses the chain | 15 min |
| Setting Prototypes | Object.create, proto, setPrototypeOf | 15 min |
| Built-in Prototypes | Array, Function, Object prototypes | 10 min |
| Prototype vs Instance | Own properties vs inherited, hasOwnProperty | 10 min |
Prerequisites
Section titled “Prerequisites”- Objects and how they work
- Functions and constructors
- Basic understanding of inheritance
Learning Path
Section titled “Learning Path”Prototype Chain → Setting Prototypes → Built-in Prototypes → Prototype vs InstanceKey Concepts
Section titled “Key Concepts”- Every object has a
[[Prototype]](internal link to another object) - Property lookup walks up the chain until found or
null Object.create()creates objects with a specific prototype- Methods on the prototype are shared across all instances
- The chain always ends at
null