Setup AsyncIteratorPrototype for Common.js Async Iterator Helpers polyfill on async generators

async-iterator-setup.mjs

const asyncGeneratorInstancePrototype = Object.getPrototypeOf(async function*(){}());
const AsyncGeneratorPrototype = Object.getPrototypeOf(asyncGeneratorInstancePrototype);
let AsyncIteratorPrototype;
if (AsyncGeneratorPrototype === Object.prototype) {
  // Fix-up for babel's transform-async-generator-functions
  AsyncIteratorPrototype = {};
  const newAsyncGeneratorPrototype = Object.create(AsyncIteratorPrototype);
  Object.setPrototypeOf(asyncGeneratorInstancePrototype, newAsyncGeneratorPrototype);
} else {
  AsyncIteratorPrototype = Object.getPrototypeOf(AsyncGeneratorPrototype);
}
import configurator from "core-js/configurator.js";
configurator({ AsyncIteratorPrototype });

Add this file to your project and import it at the top of your entry-point, to enable Async Iterator Helper polyfills from core-js on async generator functions, e.g.:

// Add this at the top of your entry point script only and before require'ing core-js async-iterator-helpers:
import "./async-iterator-setup.mjs";

import "core-js/proposals/async-iterator-helpers";

async function* gen() {
  yield* [1, 2, 3, 4, 5];
}

gen()
  .drop(1) // Using Async Iterator Helpers here works
  .take(3)
  .filter(n => n != 3)
  .map(n => n * 10)
  .forEach(n => console.log(n));