//run this in node.js, firefox only, not in browser chrome for now
const parallel = async (...items) => {
  const temp = [];
  for (const item of items) {
    temp.push(await item);
  }
  return temp;
};

const someResult = async () => {
  return new Promise((resolve, reject) => {
    console.log('running someResult() ...');
    setTimeout(() => {
      console.log('someResult() is done');
      resolve('hello');
    }, 2000);
  });
};

const anotherResult = async () => {
  return new Promise((resolve, reject) => {
    console.log('running anotherResult()...');
    setTimeout(() => {
      console.log('anotherResult() is done');
      resolve('world');
    }, 3000);
  });
};

(async () => {
  console.log('running test case');
  const t0 = new Date()
  const [p1, p2] = await parallel(someResult(), anotherResult());
  const t1 = new Date()
  console.assert(p1 == 'hello')
  console.assert(p2 == 'world')
  console.assert(t1 - t0 < 3010)
  console.log(p1, p2, t1 - t0)
  console.log('all assertion passed, someResult(), anoterResult() is executed in parallel')
})();

console.log('eof')