I don't know if this works well on JS, but there is a purely functional way that avoids most of the performance hit - generator methods. In C#, I'd write functions that return IEnumerable<T>, using yield return, and others that combine them with LINQ's Concat, and aside from many iterator objects, only one big array would need to be allocated.
When it happens that parts of this work later turn out not to be needed, it's easy to discard an enumerable, and the iteration is not actually performed. It can sometimes lead to really ellegant code that also performs well.
When it happens that parts of this work later turn out not to be needed, it's easy to discard an enumerable, and the iteration is not actually performed. It can sometimes lead to really ellegant code that also performs well.