UTC => TZ conversion works
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e4af522b88
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147
index.js
147
index.js
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@ -1,27 +1,126 @@
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/**
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* take a date of assumed timezone and convert to utc
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*
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* @param {*} d
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* @param {*} tz
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* @returns
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*/
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function tzUTC(d, tz) {
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// first calculate tz difference
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var date = new Date();
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"use strict";
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function fromUTCToTimeZone(date, timeZone) {
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// ISO string or existing date object
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date = new Date(date);
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var options = {
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year: 'numeric',
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month: 'numeric',
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day: 'numeric',
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hour: 'numeric',
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minute: 'numeric',
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second: 'numeric',
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timeZone: timeZone,
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year: "numeric",
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month: "numeric",
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day: "numeric",
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hour12: false,
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timeZone: tz
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hour: "numeric",
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minute: "numeric",
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second: "numeric",
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fractionalSecondDigits: 3,
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};
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var tzDate = new Intl.DateTimeFormat('en-US', options).format(date)
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var diff = date - new Date(tzDate);
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var minutes = Math.floor((diff / 1000) / 60);
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var localTime = new Date(d);
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localTime.setMinutes(d.getMinutes() + minutes);
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return localTime.toUTCString();
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}
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var tzOptions = Object.assign(
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{
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timeZoneName: "long",
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},
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options
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);
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// Every country uses the same year and months, right?
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var formater = new Intl.DateTimeFormat("default", tzOptions);
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var parts = formater.formatToParts(date);
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var whole = {};
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parts.forEach(function (part) {
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var val = part.value;
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switch (part.type) {
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case "literal":
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// ignore separators and whitespace characters
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return;
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case "timeZoneName":
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// keep as is - it's a string
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break;
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case "month":
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// months are 0-indexed for new Date()
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val = parseInt(val, 10) - 1;
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break;
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case "hour":
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// because sometimes 24 is used instead of 0, make 24 0
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val = parseInt(val, 10) % 24;
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break;
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case "fractionalSecond":
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// fractionalSecond is a dumb name - should be millisecond
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whole.millisecond = parseInt(val, 10);
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return;
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default:
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val = parseInt(val, 10);
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}
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// whole.month = 0;
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whole[part.type] = val;
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});
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whole.timeZone = timeZone;
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whole.offset = getOffset(date, whole);
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whole.toISOString = _toOffsetISOString;
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return whole;
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}
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function _toOffsetISOString() {
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return toOffsetISOString(this);
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}
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function getOffset(utcDate, tzD2) {
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var tzDate = new Date(toOffsetISOString(tzD2));
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var diff = Math.round(tzDate.valueOf() - utcDate.valueOf()) / (60 * 1000);
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return diff;
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}
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function p2(x) {
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return String(x).padStart(2, "0");
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}
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function p3(x) {
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return String(x).padStart(3, "0");
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}
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function formatOffset(minutes) {
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if (!minutes) {
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return "Z";
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}
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var h = Math.floor(Math.abs(minutes) / 60);
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var m = Math.abs(minutes) % 60;
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var offset = "";
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if (minutes > 0) {
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offset = "+";
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} else if (minutes < 0) {
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offset = "-";
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}
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// +0500, -0730
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return (
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offset + h.toString().padStart(2, "0") + m.toString().padStart(2, "0")
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);
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}
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function toOffsetISOString(d) {
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var offset = formatOffset(d.offset);
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return (
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`${d.year}-${p2(d.month + 1)}-${p2(d.day)}` +
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`T${p2(d.hour)}:${p2(d.minute)}:${p2(d.second)}.${p3(
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d.millisecond
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)}${offset}`
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);
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}
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function fromZonedToUTC(dt, tz) {}
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module.exports = {
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// bespoke date =>
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// 2021-11-07T3:15:59-0500
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toOffsetISOString: toOffsetISOString,
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// -240 => -0400
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formatOffset: formatOffset,
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// [ "2021-11-07T08:15:59Z", "America/New_York" ]
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// => "2021-11-07T03:15:59-0500" // 2021-11-07 03:15:59
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fromUTCToTimeZone: fromUTCToTimeZone,
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// [ "2021-11-07 03:15:59", "America/New_York" ]
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// => "2021-11-07T03:15:59-0500" // 2021-11-07T08:15:59Z
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fromZonedToUTC: fromZonedToUTC,
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};
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254
test.js
254
test.js
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@ -1,133 +1,145 @@
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var d = new Date("5/18/2019, 07:49:13");
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// Fri May 17 2019 17:49:13 GMT-0400 (Eastern Daylight Time)
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// utc should be Fri, 17 May 2019 21:49:13 GMT"
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//
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console.log("d:" + d)
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console.log("tzUTC:" + tzUTC(d, 'Australia/Sydney'))
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"use strict";
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d = new Date("5/17/2019, 14:53:21");
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console.log("d:" + d)
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var TZ = require("./");
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// Fri May 17 2019 17:53:21 GMT-0400 (Eastern Daylight Time)
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// utc "Fri, 17 May 2019 21:53:21 GMT"
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// At this real UTC time, what does the timezone translate it to?
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[
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//
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// Start-of-DST Tests
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//
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console.log("tzUTC:" + tzUTC(d, 'America/Los_Angeles'))
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// [Start]
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// What time is '2021-03-14 01:15:59.000 in New York' in UTC? // 2021-03-14 06:15:59.000
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// // 2021-03-14T01:15:59.000-0500
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// What time is '2021-03-14 02:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
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// // 2021-03-14T03:15:59.000-0400
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// What time is '2021-03-14 03:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
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// // 2021-03-14T03:15:59.000-0400
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// What time is '2021-03-14 04:15:59.000 in New York' in UTC? // 2021-03-14 08:15:59.000
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// // 2021-03-14T04:15:59.000-0400
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// [End]
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// 12:15am NY -0500 => -0400
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{
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inputs: ["2021-03-14T05:15:59.000Z", "America/New_York"],
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result: "2021-03-14T00:15:59.000-0500",
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},
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{
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inputs: ["2021-03-14T00:15:59.000-0500", "America/New_York"],
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result: "2021-03-14T00:15:59.000-0500",
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},
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// 1:15am NY (non-DST)
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{
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inputs: ["2021-03-14T06:15:59.000Z", "America/New_York"],
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result: "2021-03-14T01:15:59.000-0500",
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},
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{
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inputs: ["2021-03-14T01:15:59.000-0500", "America/New_York"],
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result: "2021-03-14T01:15:59.000-0500",
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},
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//////
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////// 9:01 twice
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//////
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// NOTE: Can't 2:15am NY, because it does not exist (skipped by DST)
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var d = new Date("3/10/2019, 01:59:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 10 Mar 2019 08:59:00 GMT
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// 3:15am NY (DST)
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{
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inputs: ["2021-03-14T07:15:59.000Z", "America/New_York"],
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result: "2021-03-14T03:15:59.000-0400",
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},
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{
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inputs: ["2021-03-14T03:15:59.000-0400", "America/New_York"],
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result: "2021-03-14T03:15:59.000-0400",
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},
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// 4:15am NY
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{
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inputs: ["2021-03-14T08:15:59.000Z", "America/New_York"],
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result: "2021-03-14T04:15:59.000-0400",
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},
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{
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inputs: ["2021-03-14T04:15:59.000-0400", "America/New_York"],
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result: "2021-03-14T04:15:59.000-0400",
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},
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var d = new Date("3/10/2019, 02:01:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 10 Mar 2019 09:01:00 GMT
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//
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// End-of-DST Tests
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//
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var d = new Date("3/10/2019, 02:59:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 10 Mar 2019 09:59:00 GMT
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// [Start]
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// What time is '2021-11-07 01:15:59.000 in New York' in UTC? // 2021-11-07 05:15:59.000
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// // 2021-11-07T01:15:59.000-0400
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// // 2021-11-07 06:15:59.000
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// // 2021-11-07T01:15:59.000-0500
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// What time is '2021-11-07 02:15:59.000 in New York' in UTC? // 2021-11-07 07:15:59.000
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// // 2021-11-07T02:15:59.000-0500
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// What time is '2021-11-07 03:15:59.000 in New York' in UTC? // 2021-11-07 08:15:59.000
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// [End]
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var d = new Date("3/10/2019, 03:01:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 10 Mar 2019 09:01:00 GMT
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// 12:15am NY -0400 => -0500
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{
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inputs: ["2021-11-07T04:15:59.000Z", "America/New_York"],
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result: "2021-11-07T00:15:59.000-0400",
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},
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{
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inputs: ["2021-11-07T00:15:59.000-0400", "America/New_York"],
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result: "2021-11-07T00:15:59.000-0400",
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},
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// 1:15am NY (DST) -0400
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// NOTE: 1:15am happens TWICE (with different offsets)
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{
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inputs: ["2021-11-07T05:15:59.000Z", "America/New_York"],
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result: "2021-11-07T01:15:59.000-0400",
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},
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{
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inputs: ["2021-11-07T01:15:59.000-0400", "America/New_York"],
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result: "2021-11-07T01:15:59.000-0400",
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},
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// 1:15am NY (non-DST) -0500
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{
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inputs: ["2021-11-07T06:15:59.000Z", "America/New_York"],
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result: "2021-11-07T01:15:59.000-0500",
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},
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{
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inputs: ["2021-11-07T01:15:59.000-0500", "America/New_York"],
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result: "2021-11-07T01:15:59.000-0500",
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},
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// 2:15am NY -0500
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{
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inputs: ["2021-11-07T07:15:59.000Z", "America/New_York"],
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result: "2021-11-07T02:15:59.000-0500",
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},
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{
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inputs: ["2021-11-07T02:15:59.000-0500", "America/New_York"],
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result: "2021-11-07T02:15:59.000-0500",
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},
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// 3:15am NY
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{
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inputs: ["2021-11-07T08:15:59.000Z", "America/New_York"],
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result: "2021-11-07T03:15:59.000-0500",
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},
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{
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inputs: ["2021-11-07T03:15:59.000-0500", "America/New_York"],
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result: "2021-11-07T03:15:59.000-0500",
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},
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//////
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////// 8:01 never
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//////
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//
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// Positive Offset Test
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//
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var d = new Date("11/03/2019, 01:59:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 03 Nov 2019 07:59:00 GMT
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var d = new Date("11/03/2019, 02:01:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 03 Nov 2019 09:01:00 GMT
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var d = new Date("11/03/2019, 02:59:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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// tzUTC:Sun, 03 Nov 2019 09:59:00 GMT
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var d = new Date("11/03/2019, 03:01:00");
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console.log("tzUTC:" + tzUTC(d, 'America/Denver'));
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tzUTC:Sun, 03 Nov 2019 10:01:00 GMT
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/*
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Yes, that's a major use case. And one that can contact people according to their timezone. The daylight savings problem most likely won't affect us. But it could.
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As a failsafe is there a way that you could detect daylight savings time and report it? Perhaps create 3 times and check that the difference on either side is exactly 1.5 hours?
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*/
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/*
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But there's a second thing, more along the lines of a scheduler:
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Given a target date in local time, produce the same local time a week later.
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"I'm having lunch with John today at 12:30 pm. Schedule a lunch next week at 12:30pm."
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The naive approach that almost always works is to simply add (7 x 24 x 60 x 60 x 1000), but that won't work if the lunch happened on either of these days:
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var d = new Date("03/07/2019, 12:30:00"); // + (7 * 24 * 60 * 60 * 1000)
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var d = new Date("11/01/2019, 12:30:00"); // + (7 * 24 * 60 * 60 * 1000)
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In both instances my simple calendar would be off by an hour.
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*/
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/*
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I think the solution will be:
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srcMs = toMs(srcLocalDate)
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targetMs = srcMs + diffMs
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targetLocalDate = toLocal(targetMs)
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targetMs += toMsAsIfUtc(srcLocalDate) - (toMsAsIfUtc(targetLocalDate) - diffMs)
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return toLocalDate(targetMs)
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*/
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(function (exports) {
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'use strict';
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exports.TEST = function (myfn) {
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var tests = [
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{ name: "normal date"
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, input: { d: '5/18/2019, 8:59:48 AM', tz: "America/Denver" }
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, expected: 1558191588007
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// 4:15am Colombo +0530 (not DST)
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{
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inputs: ["2021-03-14T08:15:59.000Z", "Asia/Colombo"],
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result: "2021-03-14T13:45:59.000+0530",
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},
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{
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inputs: ["2021-03-14T13:45:59.000+0530", "Asia/Colombo"],
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result: "2021-03-14T13:45:59.000+0530",
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},
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].forEach(function (t) {
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var result = TZ.fromUTCToTimeZone.apply(TZ, t.inputs).toISOString();
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if (t.result !== result) {
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throw new Error(
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"Invalid Conversion:\n" +
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`\tExpected: ${t.result}\n` +
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`\tActual: ${result}\n`
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);
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}
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];
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function next() {
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var t = tests.shift();
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var result;
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if (!t) {
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return true;
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}
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try {
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result = Promise.resolve(myfn(t.input));
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} catch(e) {
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result = Promise.reject(e);
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}
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result.then(function (result) {
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if (result === t.expected) {
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return true;
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}
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throw new Error(t.name + ": result did not match expected: " + JSON.stringify(result) + " vs " + JSON.stringify(t.expected));
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});
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}
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return next();
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};
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}('undefined' === typeof module ? window : module.exports));
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runner.js:
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(function (exports) {
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'use strict';
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var tzUtc = exports.tzUtc || require('./index.js').tzUtc;
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var tester = exports.TEST || require('./test.js').TEST;
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tester(tzUtc);
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}('undefined' === typeof module ? window : module.exports));
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});
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