`for await` examples

for-await-concurrrently.js

async function* iteratorGen(arr) {
  for (const i of arr) {
    if (typeof i === "function") {
      yield i();
    } else {
      yield i;
    }
  }
}

function delay(ms, value, pass = true) {
  return new Promise(function (res, rej) {
    setTimeout((v) => (pass ? res(v) : rej(v)), ms, value);
  });
}

async function main() {
  console.time("concurrently");

  const iterator = iteratorGen([
    delay(10000, 0),
    delay(200, 1),
    delay(1000, 2),
    delay(12000, 3),
  ]);
  const values = [];

  for await (let x of iterator) {
    console.group(x);
    console.log(`timestamp: ${Date.now()}`);
    console.log(`value: ${x}`);
    console.log(`previous value: ${values[x - 1]}`);
    console.groupEnd(x);

    values.push(x);
  }

  console.timeEnd("concurrently");
}

main()
  .then((r) => console.log(r))
  .catch((err) => console.log(err));

// concurrently: 12012ms - timer ended

for-await-waterfall.js

async function* iteratorGen(arr) {
  for (const i of arr) {
    if (typeof i === "function") {
      yield i();
    } else {
      yield i;
    }
  }
}

function delay(ms, value, pass = true) {
  return new Promise(function (res, rej) {
    setTimeout((v) => (pass ? res(v) : rej(v)), ms, value);
  });
}

async function main() {
  console.time("waterfall");

  const iterator = iteratorGen([
    delay.bind(null, 10000, 0),
    delay.bind(null, 200, 1),
    delay.bind(null, 1000, 2),
    //  delay.bind(null, 1000, new Error('yo'), false),
    delay.bind(null, 12000, 3),
  ]);

  const values = [];

  for await (let x of iterator) {
    console.group(x);
    console.log(`timestamp: ${Date.now()}`);
    console.log(`value: ${x}`);
    console.log(`previous value: ${values[x - 1]}`);
    console.groupEnd(x);

    values.push(x);
  }

  console.timeEnd("waterfall");
}

main()
  .then((r) => console.log(r))
  .catch((err) => console.log(err));

// waterfall: 24032ms - timer ended