forEach<T>( iteratorOrIterable: Iterable<T, any, any> | Iterator<T, any, any>, callbackfn: (currentValue: T, currentIndex: number) => void,): void 参数
- iteratorOrIterable: Iterable<T, any, any> | Iterator<T, any, any>
- callbackfn: (currentValue: T, currentIndex: number) => void
返回 void
迭代器的forEach, JS没有提供，这里写一下