superset-frontend/packages/superset-ui-core/src/time-format/utils/stringifyTimeInput.ts

export default function stringifyTimeInput(
  value: Date | number | undefined | null,
  fn: (time: Date) => string,
) {
  if (value === null || value === undefined) {
    return `${value}`;
  }

  return fn(value instanceof Date ? value : new Date(value));
}