react-date-picker/src/utils/forwardTime.js

A carefully crafted date picker for React

export default (from, to) => {
  if (from) {
    ['hour', 'minute', 'second', 'millisecond'].forEach(part => {
      to.set(part, (from.get ? from.get(part) : from[part]))
    })
  }

  return to
}