Countdown

A live countdown timer to a future moment — it re-renders every second, ticks down, never goes negative, and fires an onComplete callback once when it reaches zero. Use it wherever you're waiting on a deadline: a product/waitlist launch or "coming soon" page, a sale/offer/flash-deal or cart-reservation expiry, an OTP/verification resend or rate-limit cooldown, an auction or bid close, a webinar/event/stream start time, a maintenance window, a booking or checkout hold, or a quiz/game round timer. Pass `to` as a Date, an ISO string, or epoch milliseconds. By default it renders labeled days/hours