How the countdown timer works
You pick a target date and time, and the page works out how much is left and refreshes it once per second. The count is broken down into days, hours, minutes and seconds, the most intuitive way to read "how long to go." All the math runs in your browser with the JavaScript date API: it takes the current instant, subtracts it from the target instant, and turns that difference in milliseconds into readable units. When the difference hits zero or goes negative, the countdown stops and tells you the moment has arrived.
What a countdown is good for
- Launches: a product, a website or a campaign going live at an exact time.
- Events: a birthday, a wedding, a concert or kickoff.
- Deadlines: a registration close, a project hand-in or the end of a promo.
- Holidays and special dates: how long until New Year, the holidays or a trip.
- Personal goals: the day you start something new or a streak ends.
Sharing the countdown with a link
The "Copy shareable link" button doesn’t just copy the page address: it stores the target date (and the title, if you set one) inside the link’s hash, the part after the #. When that link is opened, the page reads the hash and starts the same countdown automatically, with nothing for the other person to enter. Because the hash is never sent to the server, the date and title stay only between you and whoever receives the link.
Time zones: what you actually see
The date field uses your device’s local time. Internally the countdown converts that time to an absolute instant (the same point on the global timeline). So if you share the link with someone in another time zone, they see the countdown pointing at the same real moment, adjusted to their clock. If your event is "8:00 PM in New York," make sure you pick that time on a device in that zone, or communicate the zone, to avoid confusion.
Privacy and offline behavior
There are no servers involved: the countdown is plain JavaScript running in your browser. The target date only leaves your device if you copy the shareable link, and even then it travels in the URL hash, which is not sent in HTTP requests. Once the page has loaded, the countdown keeps ticking even if you lose your connection.
Reference: common durations in seconds
The countdown converts everything to seconds internally. This table shows how large those numbers get:
| Duration | Seconds | Equivalent |
|---|---|---|
| 1 minute | 60 | — |
| 1 hour | 3,600 | 60 minutes |
| 1 day | 86,400 | 24 hours |
| 1 week | 604,800 | 7 days |
| 30 days | 2,592,000 | ≈ 1 month |
| 365 days | 31,536,000 | 1 year |