Understanding "for await...of"

for-await-of.js

const arr = []

const dummy = async function (i) {
  return new Promise((res, rej) => {
    const delay =  Math.random() * 1000
    setTimeout(() => {
      console.log('%s, delayed: %s, timestamp: %s', i, delay, Date.now());
      res(i);
    }, delay);
  });
}
for (let i = 0; i< 10; i++) {
  arr.push(dummy(i))
}

(async () => {
  const start = Date.now();
  for await (const res of arr) {
    console.log('%s, timestamp: ', res, Date.now())
  }
  console.log('Total duration: %s ms', Date.now() - start);
})()