@open-rlb/date-tz/helpers.js

A lightweight JavaScript/TypeScript date-time utility with full timezone support, custom formatting, parsing, and manipulation features.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.getOffsetSeconds = getOffsetSeconds;
exports.tzDiscover = tzDiscover;
const canonical_link_1 = require("./canonical-link");
function getOffsetSeconds(timestamp, timezone) {
    if (timezone === 'UTC')
        return 0;
    const baseOffset = tzDiscover(timestamp, timezone).offset;
    let timestampdiscovery = timestamp - (baseOffset - 60) * 60 * 1000;
    const arr = [];
    const interval = 4;
    timestampdiscovery -= interval * 15 * 60 * 1000;
    for (const time2discover of Array.from({ length: interval * 2 }, (_, i) => timestampdiscovery + i * 15 * 60 * 1000)) {
        arr.push(tzDiscover(time2discover, timezone));
    }
    const first = arr[0];
    const last = arr[arr.length - 1];
    const delta = last.offset - first.offset;
    if (delta === 0)
        return first.offset * 60;
    if (delta > 0) {
        return first.offset * 60;
    }
    if (delta < 0) {
        return last.offset * 60;
    }
}
function tzDiscover(timestamp, timezone) {
    const formatterTZS = new Intl.DateTimeFormat('en-US', { timeZone: timezone, timeZoneName: 'longOffset', hour12: false, year: 'numeric', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit', second: '2-digit', });
    const formatterTZL = new Intl.DateTimeFormat('en-US', { timeZone: timezone, timeZoneName: 'long', hour12: false, year: 'numeric', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit', second: '2-digit', });
    const partsTZS = formatterTZS.formatToParts(timestamp);
    const partsTZL = formatterTZL.formatToParts(timestamp);
    const longName = getTimeFormatPart(partsTZL, 'timeZoneName')?.toLowerCase();
    const isDst = longName.includes('summer') || longName?.includes('daylight');
    const _timezone = getTimeFormatPart(partsTZS, 'timeZoneName');
    if (_timezone === 'UTC' || _timezone === 'GMT')
        return { isDst: false, offset: 0 };
    const match = _timezone.match(/^(?:GMT|UTC)?([+-])(\d{1,2})(?::(\d{2}))?$/i);
    if (!match) {
        throw new Error(`Unexpected timeZoneName format: ${_timezone}`);
    }
    const sign = match[1] === '+' ? 1 : -1;
    const hours = parseInt(match[2], 10);
    const mins = match[3] ? parseInt(match[3], 10) : 0;
    return { isDst, offset: sign * (hours * 60 + mins), hh: `${getTimeFormatPart(partsTZS, 'hour')}:${getTimeFormatPart(partsTZS, 'minute')}` };
}
function getTimeFormatPart(parts, type) {
    const part = parts.find(p => p.type === type);
    if (!part) {
        throw new Error(`Missing part ${type}`);
    }
    return part.value;
}
;
function supportedTimeZones() {
    const canonical = Array.from(new Set([
        ...canonical_link_1.etc,
        ...Intl.supportedValuesOf('timeZone')
    ]));
    return canonical;
}
function fallbackTimeZone(timezone) {
    if (supportedTimeZones().includes(timezone)) {
        return timezone;
    }
    else if (Object.keys(canonical_link_1.canonicalLink).includes(timezone) && supportedTimeZones().includes(canonical_link_1.canonicalLink[timezone])) {
        return canonical_link_1.canonicalLink[timezone];
    }
    else if (Object.values(canonical_link_1.canonicalLink).includes(timezone) && supportedTimeZones().includes(Object.entries(canonical_link_1.canonicalLink).find(([k, v]) => v === timezone)?.[0])) {
        return Object.entries(canonical_link_1.canonicalLink).find(([k, v]) => v === timezone)?.[0];
    }
    else {
        throw new Error(`Unsupported time zone: ${timezone}`);
    }
}
//# sourceMappingURL=helpers.js.map