SeriesAsync.js

// Given series of async functions and you need to execute sequentially

function a1(callback) {
  setTimeout(() => {
    console.log("hello Mounika");
    callback();
  }, 1000);
}

function a2() {
  setTimeout(() => {
    console.log("hello Sudhakar");
  }, 0);
}

// One approach is you need to recursively go and execute functions

const arrayAsync = [a1, a2];

function seriesAsync(currentIndex) {
  if (currentIndex < arrayAsync.length) {
    arrayAsync[currentIndex](function () {
      seriesAsync(currentIndex + 1);
    });
  }
}

// But usually it will be given in promises only
// so we can use for of with await

for (const promise of arrayAsync) {
  await promise;
}
// this will make synchronous as we are using await which will not allow

seriesAsync(0);