// This tests Object.create, Object.defineProperty, Object.defineProperties work with Symbol. function testSymbol(object) { if (!object.hasOwnProperty(Symbol.iterator)) throw "Error: object doesn't have Symbol.iterator"; if (object.propertyIsEnumerable(Symbol.iterator)) throw "Error: Symbol.iterator is defined as enumerable"; if (JSON.stringify(Object.getOwnPropertyDescriptor(object, Symbol.iterator)) !== '{"value":42,"writable":false,"enumerable":false,"configurable":false}') throw "Error: bad property descriptor " + JSON.stringify(Object.getOwnPropertyDescriptor(object, Symbol.iterator)); if (Object.getOwnPropertySymbols(object).length !== 1) throw "Error: bad value " + Object.getOwnPropertySymbols(object).length; if (Object.getOwnPropertySymbols(object)[0] !== Symbol.iterator) throw "Error: bad value " + String(Object.getOwnPropertySymbols(object)[0]); } var object = Object.create(Object.prototype, { [Symbol.iterator]: { value: 42 } }); testSymbol(object); var object = Object.defineProperties({}, { [Symbol.iterator]: { value: 42 } }); testSymbol(object); var object = Object.defineProperty({}, Symbol.iterator, { value: 42 }); testSymbol(object);