JavaScript Native Contracts

• Callable — Any value that can be invoked with () operator
  • Examples: 0-callable.js
• Function — Callable object, with optional this binding or arrow
  • Examples: Function
• AsyncFunction — Promise-returning Function
  • Examples: AsyncFunction
• Callback — A function passed to another function to be called later. Callback-last-error-first — Callback contract or convention (error, result) signature, where error is Error | null, and result is returned if no error
  • Examples: 1-callback.js, Callbacks
• Thenable — Any object with a .then(fn) method
  • Examples: 3-thenable.js, Thenable
• Promise — Thenable with then, catch, and finally
  • Examples: 4-promise.js, Promise
• Iterable — Has [Symbol.iterator]() that returns an Iterator
  • Examples: 5-iterable.js
• AsyncIterable — Has [Symbol.asyncIterator]() that returns an AsyncIterator
  • Examples: 6-async.js
• Iterator — Has .next() returning { value, done } structure
  • Examples: AsyncIterator, Iterator
• Generator — A function producing an Iterator (sync or async), supporting next(), throw(), return()
  • Examples: 7-generator.js, Generator, AsyncGenerator
• Array-like — Object with indexed keys 0, 1, ... and numeric .length, but no array methods
  • Examples: 8-array-like.js
• Observable — Push-based data sours available for subscription
  • Examples: 9-observable.js, Events, Observer
• EventTarget — DOM standard interface with .addEventListener(event, handler)
• EventEmitter — Node.js style event emitter with .on(event, handler) and .emit(event, ...args)
  • Examples: EventEmitter,
• Stream — Abstraction for flow (readable/writable/duplex) with backpressure support
  • Examples: a-stream.js, Streams