asyncPerformance

const foo = async function() {
  const timeAtBeginning = new Date().getTime();
  const vals = [];
  for(let a of [1, 2, 3]) {
    vals.push(
      await new Promise( r => setTimeout(r, 1000, a * 2) )
    );
  }
  const timeAtEnd = new Date().getTime() - timeAtBeginning;
  console.log(vals, timeAtEnd);
};


const bar = async function() {
  const timeAtBeginning = new Date().getTime();
  const vals = await Promise.all(
    [1, 2, 3].map(
      async a => new Promise( r => setTimeout(r, 1000, a * 2) )
    )
  );
  const timeAtEnd = new Date().getTime() - timeAtBeginning;
  console.log(vals, timeAtEnd);
};

foo();
bar();