Created
July 15, 2021 05:18
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export const getGmtDiff = (timeZone: typeof IANNA_TIME_ZONES[number]["key"]) => { | |
const date = new Date(); | |
const GMT_TIME_UTC_DATE = date.getUTCDate(); | |
const GMT_TIME_HOURS = date.getUTCHours(); | |
const GMT_TIME_MIN = date.getUTCMinutes(); | |
const timeZoneDate = new Date(new Date().toLocaleString("en-US", { timeZone })); | |
const h = timeZoneDate.getHours(); | |
// NOTE: Remember that adding a negative number subtracts | |
let dateLineOffset = 0; | |
if (timeZoneDate.getDate() < GMT_TIME_UTC_DATE) dateLineOffset = -24; | |
if (timeZoneDate.getDate() > GMT_TIME_UTC_DATE) dateLineOffset = 24; | |
const hrs = h - GMT_TIME_HOURS + dateLineOffset; | |
let plusOrMinus = " "; | |
if (hrs > 0) plusOrMinus = "+"; | |
if (hrs < 0) plusOrMinus = "-"; | |
// NOTE: Remember that adding a negative number subtracts | |
const minDiff = timeZoneDate.getMinutes() - GMT_TIME_MIN; | |
const hrsAccountingMinutes = minDiff < 0 ? hrs + minutes(minDiff).in("hours") : hrs; | |
// NOTE: Remember that adding a negative number subtracts | |
const finalHours = String(Math.abs(Math.floor(hrsAccountingMinutes))).padStart(2, "0"); | |
const finalMinutes = String(minDiff < 0 ? 60 + minDiff : minDiff).padStart(2, "0"); | |
return `(GMT${plusOrMinus}${finalHours}:${finalMinutes})`; | |
}; |
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