Web pack enabled web workers

testFunction.ts

export const testFunction = () => {
    return Array(1000).fill(2).map((n, i) => n * i).map((n, i) => n * i ** 2)
}

worker.ts

import { testFunction } from './testFunction';

onmessage = function (e: MessageEvent<{ args: Parameters<typeof testFunction> }>) {
  const result = formatFeatures(...e.data.args);
  postMessage(result);
};

workerWrapper.ts

import { testFunction } from './testFunction';

export async function testFunctionWebWorker(
  ...args: Parameters<typeof testFunction>
): Promise<ReturnType<typeof testFunction>> {
  const worker = new Worker(new URL('./worker.ts', import.meta.url));

  return new Promise<ReturnType<typeof testFunction>>((resolve, reject) => {
    worker.onmessage = function (e: MessageEvent<ReturnType<typeof testFunction>>) {
      resolve(e.data);
      worker.terminate();
    };

    worker.onerror = function (e: ErrorEvent) {
      reject(e);
      worker.terminate();
    };

    worker.postMessage({ args });
  });
}