limiting JS promise concurrency

gen.js

async function* mapWithLimitedConcurrency(arr, mapFn, limit = 8) {
    for (let i = 0; i < arr.length; i += limit) {
        yield await Promise.all(arr.slice(i, i + limit).map(mapFn));
    }
}

const items = [...]

const iterator = mapWithLimitedConcurrency(items, async x => ...);

for await(const items of iterator) {
    ...
}