Prototype Chain
The prototype chain is JavaScript's object inheritance mechanism: objects look up properties along the __proto__ chain, up to null.
Purpose
Understand JS object inheritance and property lookup, and use prototypes correctly.
Mechanism
Reading a property walks the prototype chain: obj → obj.__proto__ → ... → Object.prototype → null. Writing creates the property on the object itself. Object.create/assign and class syntax manipulate the prototype chain.
Use cases
- JavaScript objects
- Inheritance mechanism
- Prototype methods