https://github.com/nilicule/timezone
Timezone World Board
https://github.com/nilicule/timezone
Last synced: 1 day ago
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Timezone World Board
- Host: GitHub
- URL: https://github.com/nilicule/timezone
- Owner: nilicule
- Created: 2026-06-30T15:57:18.000Z (3 days ago)
- Default Branch: main
- Last Pushed: 2026-06-30T16:07:46.000Z (3 days ago)
- Last Synced: 2026-06-30T18:07:42.782Z (3 days ago)
- Language: HTML
- Size: 301 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
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Metadata Files:
- Readme: README.md
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README
# Timezone World Board
A single self-contained webpage for seeing the time around the world and
converting a reference time (e.g. "12 PM ET tomorrow") into every location's
local time — no more manual timezone math.
## Usage
Open `index.html` in any browser. That's it — no build step, no server, and it
works offline.
When deploying (hosted at `https://n2g.dev/timezone/`), upload `og-card.png`
alongside `index.html` so the social/Slack preview image resolves. The Open
Graph URLs in `index.html` point at that path — update them if the host changes.
## What it does
- **Now (live)** — every location ticks in real time.
- **Reference time** — enter a time, a date (Today / Tomorrow / pick), and the
zone it's in (type `ET`, `PT`, `Tokyo`, an IANA name, …). The whole board
recomputes to show that single instant everywhere.
- **World map** with a pin per location, colored by working / awake / asleep,
plus day/night shading that tracks the displayed time.
- **Timezone regions** — faint offset bands on the map; hover one to see its
current (DST-aware) offset and time. Toggle with the "Timezone zones" checkbox.
- **City cards** — 12- and 24-hour time, date, timezone abbreviation, UTC
offset, and a work/sleep status, sorted west → east.
- **Editable locations** — add any of ~170 cities (or any IANA zone), remove
with the ✕, "Reset to defaults" restores the starting set. Your list and
preferences are saved in the browser (`localStorage`).
## How it works
All timezone math uses the browser's built-in `Intl` API, so DST, abbreviations,
and offsets are always correct without any bundled timezone database. The map is
inline SVG; cities are projected by latitude/longitude, and the day/night
terminator is computed from the sun's position at the displayed instant.
## Notes
- Timezone bands are the cartographic offset regions (generalized shapes). The
per-city **cards** are the source of truth for an exact location.
- Everything lives in `index.html` — geometry and data are embedded.
## Credits
Map and timezone geometry from
[Natural Earth](https://www.naturalearthdata.com/) (public domain).