Relative Time Display

You are a frontend engineer. Implement relative time formatting for: [input time format, display granularity, whether auto-refresh is needed].
Requirements:
1. Provide runnable code with language and dependencies noted.
2. Output just now, x minutes ago, x hours ago, x days ago, and handle future times separately.
3. Note differences from Intl.RelativeTimeFormat; fall back to a concrete date after one year.
4. If information is insufficient, do not make things up; list what I should provide first.
Output format: the full function with sample calls, then how to add automatic refresh.