Construct and convert date object from datetime-local input

date.jsx

const [myDate, setMyDate] = useState()

const pad2 = (num: number): string => num < 10 ? '0' + num : num.toString();

const utcAsLocalString = (date: Date | undefined): string | undefined => {
  if (date == null) return undefined;
  return (date.getFullYear() + '-' + pad2(date.getMonth()) + '-' + date.getDate() + 'T' + pad2(date.getHours()) + ':' + pad2(date.getMinutes()) + ':' + pad2(date.getSeconds())) 
}

<input
  type="datetime-local"
  class="form-control"
  onChange={(e) => setMyDate(new Date((e.target as any).value))}
  value={myDate ? utcAsLocalString(myDate) : null}
  onFocus={() => {}}
/>