@thi.ng/transducers-async/merge.js

Async versions of various highly composable transducers, reducers and iterators

import { __inflightIters, __iterNext, __iterRemove } from "./internal/iter.js";
async function* merge(src) {
  const iters = src.map((v, id) => ({ id, iter: v[Symbol.asyncIterator]() }));
  const promises = __inflightIters(iters);
  while (true) {
    const { iter, res } = await Promise.race(promises);
    if (res.done) {
      promises.splice(iter.id, 1);
      if (__iterRemove(iters, iter.id)) return;
    } else {
      yield res.value;
      __iterNext(promises, iter);
    }
  }
}
export {
  merge
};