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Pages: /, /simple, /decimal, /seth, /calendar, /astro, /convert, /timegov Features: Seth Calendar (10×36 + holidays), decimal time, moon phases, astronomy (sun/moon), bidirectional time converter, Seth date display, leap day split cell in calendar grid.
281 lines
8.9 KiB
JavaScript
281 lines
8.9 KiB
JavaScript
// Decimal time & French Republican Calendar
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//
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// Decimal time: 1 day = 10 decimal hours
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// 1 decimal hour = 100 decimal minutes
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// 1 decimal minute = 100 decimal seconds
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//
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// French Republican Calendar epoch: 22 September 1792 (Gregorian) = 1 Vendémiaire An I
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// Each year has 12 months of 30 days + 5 (or 6 in sextile years) complementary days.
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// Sextile (leap) years: the Republican leap rule approximates the Gregorian one —
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// years 3, 7, 11, 15, 20 of each 20-year cycle were designated sextile in the original
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// Romme proposal. For simplicity we use the widely accepted rule:
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// A Republican year is sextile if the *following* Gregorian year is a Gregorian leap year.
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const REPUBLICAN_EPOCH_JD = 2375840; // Julian Day Number of 1 Vendémiaire An I (22 Sep 1792)
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const MONTH_NAMES = [
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"Vendémiaire", "Brumaire", "Frimaire",
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"Nivôse", "Pluviôse", "Ventôse",
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"Germinal", "Floréal", "Prairial",
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"Messidor", "Thermidor", "Fructidor"
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];
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const MONTH_NAMES_EN = [
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"Vintage", "Mist", "Frost",
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"Snowy", "Rainy", "Windy",
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"Budding", "Flowery", "Meadow",
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"Harvest", "Heat", "Fruit"
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];
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const COMPLEMENTARY_NAMES = [
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"Jour de la Vertu", // 1
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"Jour du Génie", // 2
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"Jour du Travail", // 3
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"Jour de l'Opinion", // 4
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"Jour des Récompenses", // 5
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"Jour de la Révolution", // 6 (sextile only)
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];
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const COMPLEMENTARY_NAMES_EN = [
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"Day of Virtue",
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"Day of Genius",
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"Day of Labour",
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"Day of Opinion",
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"Day of Rewards",
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"Day of the Revolution",
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];
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const WEEKDAY_NAMES = [
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"Primidi", "Duodi", "Tridi", "Quartidi", "Quintidi",
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"Sextidi", "Septidi", "Octidi", "Nonidi", "Décadi"
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];
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const WEEKDAY_NAMES_EN = [
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"First day", "Second day", "Third day", "Fourth day", "Fifth day",
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"Sixth day", "Seventh day", "Eighth day", "Ninth day", "Tenth day"
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];
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// --- Julian Day Number helpers ---
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function gregorianToJD(year, month, day) {
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// Algorithm from Jean Meeus, "Astronomical Algorithms"
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if (month <= 2) { year -= 1; month += 12; }
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const A = Math.floor(year / 100);
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const B = 2 - A + Math.floor(A / 4);
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return Math.floor(365.25 * (year + 4716)) +
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Math.floor(30.6001 * (month + 1)) +
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day + B - 1524.5;
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}
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function isGregorianLeap(year) {
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return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
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}
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function isSextile(republicanYear) {
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// The year following An N is Gregorian year 1792 + N
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return isGregorianLeap(1792 + republicanYear);
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}
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function toRepublicanDate(utcDate) {
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// JD at midnight UTC for the given date
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const jd = Math.floor(gregorianToJD(
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utcDate.getUTCFullYear(),
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utcDate.getUTCMonth() + 1,
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utcDate.getUTCDate()
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) + 0.5); // +0.5 because JD starts at noon; floor gives previous midnight
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const daysSinceEpoch = jd - REPUBLICAN_EPOCH_JD;
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if (daysSinceEpoch < 0) {
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return null; // Before the Republic
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}
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// Walk years: each year is 365 or 366 days
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let year = 1;
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let remaining = daysSinceEpoch;
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while (true) {
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const yearLen = isSextile(year) ? 366 : 365;
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if (remaining < yearLen) break;
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remaining -= yearLen;
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year++;
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}
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let month, day, weekday, complementary;
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if (remaining < 360) {
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// Normal months (0-indexed day within year)
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month = Math.floor(remaining / 30) + 1; // 1..12
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day = (remaining % 30) + 1; // 1..30
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weekday = ((remaining % 10)); // 0..9 → Primidi..Décadi
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complementary = null;
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} else {
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// Complementary days (jours complémentaires / sans-culottides)
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const compIdx = remaining - 360; // 0..4 (or 0..5 sextile)
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month = null;
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day = compIdx + 1;
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weekday = null;
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complementary = COMPLEMENTARY_NAMES[compIdx] || "Jour inconnu";
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}
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return { year, month, day, weekday, complementary };
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}
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function toRomanNumeral(n) {
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const vals = [1000,900,500,400,100,90,50,40,10,9,5,4,1];
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const syms = ["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"];
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let result = "";
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for (let i = 0; i < vals.length; i++) {
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while (n >= vals[i]) { result += syms[i]; n -= vals[i]; }
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}
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return result;
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}
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function formatRepublicanDate(r) {
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if (!r) return { full: "Before the Republic", translation: "", dayOfYear: "-", year: "-" };
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let full, translation;
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if (r.complementary) {
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const compIdx = r.day - 1;
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full = `${r.complementary}, An ${toRomanNumeral(r.year)}`;
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translation = `${COMPLEMENTARY_NAMES_EN[compIdx]}, Year ${r.year}`;
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} else {
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const weekdayName = WEEKDAY_NAMES[r.weekday];
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const weekdayNameEn = WEEKDAY_NAMES_EN[r.weekday];
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const monthName = MONTH_NAMES[r.month - 1];
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const monthNameEn = MONTH_NAMES_EN[r.month - 1];
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full = `${weekdayName}, ${r.day} ${monthName} An ${toRomanNumeral(r.year)}`;
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translation = `${weekdayNameEn}, ${r.day} ${monthNameEn}, Year ${r.year}`;
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}
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const dayOfYear = r.complementary
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? `360 + ${r.day} (Jour complémentaire)`
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: `${(r.month - 1) * 30 + r.day}`;
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return { full, translation, dayOfYear, year: `An ${toRomanNumeral(r.year)}` };
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}
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// --- Decimal time ---
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// Decimal time counts from local midnight in the selected time zone.
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function getLocalParts(date, zone) {
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const fmt = new Intl.DateTimeFormat("en-US", {
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timeZone: zone,
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hour12: false,
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year: "numeric", month: "2-digit", day: "2-digit",
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hour: "2-digit", minute: "2-digit", second: "2-digit"
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});
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const parts = fmt.formatToParts(date).reduce((acc, p) => {
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if (p.type !== "literal") acc[p.type] = parseInt(p.value, 10);
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return acc;
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}, {});
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return parts; // { year, month, day, hour, minute, second }
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}
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function toDecimalTime(date, zone) {
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const p = getLocalParts(date, zone);
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// ms since local midnight (ignoring DST transitions within the day — good enough)
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const msIntoDay =
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p.hour * 3_600_000 +
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p.minute * 60_000 +
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p.second * 1_000 +
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date.getMilliseconds();
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const dayFraction = msIntoDay / 86_400_000;
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const totalDecimalSeconds = dayFraction * 100_000; // 10h * 100m * 100s
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const dHour = Math.floor(totalDecimalSeconds / 10_000);
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const rem1 = totalDecimalSeconds % 10_000;
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const dMin = Math.floor(rem1 / 100);
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const dSec = rem1 % 100;
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const dCenti = Math.floor((dSec % 1) * 100);
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const dSecInt = Math.floor(dSec);
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return {
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str: `${dHour}:${String(dMin).padStart(2,"0")}:${String(dSecInt).padStart(2,"0")}.${String(dCenti).padStart(2,"0")}`
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};
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}
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function toRepublicanDateLocal(date, zone) {
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const p = getLocalParts(date, zone);
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return toRepublicanDate(new Date(Date.UTC(p.year, p.month - 1, p.day)));
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}
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// --- DOM & sync ---
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const zoneSelect = document.getElementById("zoneSelect");
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const zoneLabel = document.getElementById("zoneLabel");
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const dateTrans = document.getElementById("dateTrans");
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const offsetLabel = document.getElementById("offsetLabel");
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const decimalUtc = document.getElementById("decimalUtc");
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const dayOfYear = document.getElementById("dayOfYear");
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const repYear = document.getElementById("repYear");
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const utcLabel = document.getElementById("utcLabel");
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const dateLine = document.getElementById("dateLine");
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const digital = document.getElementById("digital");
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const zones = [
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"America/New_York",
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"America/Chicago",
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"America/Denver",
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"America/Los_Angeles",
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"America/Anchorage",
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"Pacific/Honolulu",
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"UTC"
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];
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let selectedZone = Intl.DateTimeFormat().resolvedOptions().timeZone || "America/New_York";
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if (!zones.includes(selectedZone)) selectedZone = "America/New_York";
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for (const zone of zones) {
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const option = document.createElement("option");
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option.value = zone;
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option.textContent = zone;
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if (zone === selectedZone) option.selected = true;
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zoneSelect.appendChild(option);
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}
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zoneSelect.addEventListener("change", () => {
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selectedZone = zoneSelect.value;
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zoneLabel.textContent = selectedZone;
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});
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let serverOffsetMs = 0;
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async function syncWithServer() {
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const start = Date.now();
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try {
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const response = await fetch(`/api/time?ts=${start}`, { cache: "no-store" });
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const end = Date.now();
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const data = await response.json();
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const rtt = end - start;
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serverOffsetMs = (data.epoch_ms + rtt / 2) - end;
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offsetLabel.textContent = `Synchronized (${serverOffsetMs >= 0 ? "+" : ""}${serverOffsetMs.toFixed(0)} ms, RTT ${rtt} ms)`;
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} catch (_) {
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offsetLabel.textContent = "Sync failed";
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}
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}
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function render() {
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const now = new Date(Date.now() + serverOffsetMs);
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const dt = toDecimalTime(now, selectedZone);
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const rep = toRepublicanDateLocal(now, selectedZone);
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const fmt = formatRepublicanDate(rep);
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digital.textContent = dt.str;
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dateLine.textContent = fmt.full;
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dateTrans.textContent = fmt.translation;
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decimalUtc.textContent = dt.str;
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dayOfYear.textContent = fmt.dayOfYear;
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repYear.textContent = fmt.year;
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zoneLabel.textContent = selectedZone;
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utcLabel.textContent = now.toISOString().replace("T", " ").replace("Z", " UTC");
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requestAnimationFrame(render);
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}
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syncWithServer();
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setInterval(syncWithServer, 20_000);
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render();
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