JS Built-in: Object, Function, Array, Error #97

Implement the core built-in constructors and their prototype methods: Object, Function, Array, and Error.

Scope#

Object#

• Object() constructor and Object.create(proto, props)
• Object.keys(), Object.values(), Object.entries()
• Object.assign(target, ...sources)
• Object.defineProperty(), Object.defineProperties()
• Object.getOwnPropertyDescriptor(), Object.getOwnPropertyNames()
• Object.getPrototypeOf(), Object.setPrototypeOf()
• Object.freeze(), Object.seal(), Object.isFrozen(), Object.isSealed()
• Object.is()
• Object.prototype.hasOwnProperty(), Object.prototype.toString(), Object.prototype.valueOf()

Function#

• Function() constructor (basic — can defer full eval)
• Function.prototype.call(thisArg, ...args)
• Function.prototype.apply(thisArg, argsArray)
• Function.prototype.bind(thisArg, ...args)
• Function.prototype.toString() (return source or "[native code]")
• name and length properties

Array#

• Array() constructor, Array.isArray(), Array.from(), Array.of()
• Mutating: push, pop, shift, unshift, splice, sort, reverse, fill, copyWithin
• Non-mutating: concat, slice, join, flat, flatMap
• Iteration: forEach, map, filter, reduce, reduceRight, find, findIndex, some, every
• Search: indexOf, lastIndexOf, includes
• Array length property (auto-updating)
• Sparse array support (basic)

Error#

• Error(message) constructor with message and stack properties
• Subclasses: TypeError, ReferenceError, SyntaxError, RangeError, URIError, EvalError
• Error.prototype.toString() — "ErrorType: message"
• Stack trace capture on construction

Acceptance Criteria#

• Object static methods and prototype methods work correctly
• Function.prototype.call/apply/bind work
• Array methods produce correct results (test each category)
• Array length updates on mutation
• Error types construct with message and stack
• Error subclasses have correct prototype chain
• Unit tests for each built-in method

Phase 10 — JavaScript Engine (issue 8 of 15). Depends on: JS Functions/closures/scoping.