Discussion on: Using Python range() in JavaScript

[Jakub T. Jankiewicz]

Your code is really weird you mix iterator protocol with generators. You just can use this, it will do the same:

function* range(start, stop) {
    if (stop === undefined) {
        stop = start
        start = 0
    }
    for (let n = start; n < stop; ++n) yield n;
}

I've also written an article on higer order iterators including async but in Polish (you can use translate option to read it).

Generatory i Iteratory wyższego poziomu

[lionel-rowe]

Not weird at all, it's a common pattern. That way, you can easily extend your range objects with other properties, like min, max, includes, etc.

More importantly, it also ensures you don't accidentally mutate the range and get unexpected results. With your version:

const r = range(1, 10)
;[...r] // [1, 2, 3, 4, 5, 6, 7, 8, 9], as expected
;[...r] // [], empty array, because the iterator has already been consumed

With my version:

const r = range(1, 10)
;[...r] // [1, 2, 3, 4, 5, 6, 7, 8, 9], as expected
;[...r] // [1, 2, 3, 4, 5, 6, 7, 8, 9], same as before

You can still get a mutable iterator from my version if you really need one, though. You just have to ask for it explicitly:

const i = range(1, 10)[Symbol.iterator]()
;[...i] // [1, 2, 3, 4, 5, 6, 7, 8, 9]
;[...i] // []