// individual calls
(async () => {
  console.time('Individual calls');
  const fetchValue = val =>
    new Promise(resolve => {
      setTimeout(() => resolve(val * 100), 500);
    });

  const value1 = await fetchValue(1);
  const value2 = await fetchValue(2);
  const value3 = await fetchValue(3);

  console.log(value1, value2, value3);
  const end = new Date().getTime();
  console.timeEnd('Individual calls');
})();

// promise all
(async () => {
  console.time('Promise all');
  const fetchValue = val =>
    new Promise(resolve => {
      setTimeout(() => resolve(val * 100), 500);
    });

  const [value1, value2, value3] = await Promise.all([
    fetchValue(1),
    fetchValue(2),
    fetchValue(3)
  ]);

  console.log(value1, value2, value3);
  const end = new Date().getTime();
  console.timeEnd('Promise all');
})();