Unfortunately not in a way that can optimize these methods. This is one reason the Java Streams API, which has a similar purpose (e.g. map, filter, flatMap, reduce, etc.), is a better design IMO because you can chain together method calls without creating (and iterating) the full array at each step.

That's incorrect. All of those functions are implemented using iteration.

Consider this excerpt from the .map() polyfill on MDN:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

    // 7. Let k be 0
    k = 0;

    // 8. Repeat, while k < len
    while (k < len) {
      // [loop body omitted]

      // d. Increase k by 1.
      k++;
    }