Revision Sheet
Object Model
Prototype chains, descriptors, classes, and object shapes explain how JavaScript stores, finds, shares, and optimizes object behavior.
Language Protocols
Symbols and iterators show how ordinary objects can participate in built-in syntax such as for...of, spread, and destructuring.
Async Internals
Promise resolution, thenables, chaining, errors, and microtasks explain why async code behaves the way it does.