Executes a given `fn` at the beginning of the next second

next-second.js

/**
 * Executes a given `fn` at the beginning of the next second.
 * @param {function} fn – a function to execute
 * @return {number} setTimeout's resulting timeout id, to give ability to cancel execution
 */
function nextSecond(fn) {
  const time = (new Date()).getTime();
  return setTimeout(fn, (Math.ceil(time / 1000) * 1000) - time);
}