Get unique timestamp as number in JavaScript.

getUniqueTimstampAsync.js

const sleepAsync = (ms) => (new Promise((resolve) => (setTimeout(resolve, ms))));

const getUniqueTimstampAsync = (function () {
  let prev;
  return async function () {
    let timestamp = +(new Date());
    while (prev === timestamp) {
      await sleepAsync(1);
      timestamp = +(new Date());
    }
    prev = timestamp;
    return timestamp;
  };
} ());

export default getUniqueTimstampAsync;