fix typo, clarify comment

add build command
fix bad description
2024-11-16 17:29:01 +00:00 · 2021-05-28 08:37:35 -06:00 · 2021-05-28 08:28:18 -06:00 · 2021-05-28 08:28:01 -06:00 · 2021-05-28 08:08:53 -06:00 · 2021-05-28 02:16:33 -06:00
9 changed files with 763 additions and 580 deletions
--- a/.prettierignore
+++ b/.prettierignore
@ -0,0 +1 @@
+*.min.js
--- a/.prettierrc.json
+++ b/.prettierrc.json
@ -0,0 +1,7 @@
+{
+  "printWidth": 80,
+  "tabWidth": 2,
+  "singleQuote": false,
+  "bracketSpacing": true,
+  "semi": true
+}
--- a/README.md
+++ b/README.md
@ -1,10 +1,12 @@
 # [xtz.js](https://github.com/therootcompany/tz.js)

-A fast, lightweight, zero-dependency library to
-translate between Time Zones and UTC with native
-`Intl.DateTimeFormat` in ~100 LoC. For Node.js & Browsers.
+A fast, lightweight, zero-dependency library to translate between Time Zones and UTC with native `Intl.DateTimeFormat`
+in ~100 LoC. For Node.js & Browsers.

-XTZ is a poor man's Temporal polyfill, but just for time zones.
+[![](./xtz-preview.png)](https://therootcompany.github.io/tz.js/)
+
+XTZ is a poor man's `Temporal` polyfill, but just for time zones. \
+Demo: <https://therootcompany.github.io/tz.js/>

 > What UTC time will it be when it's 3:15am in New York?

@ -17,7 +19,7 @@ TZ.toUTCISOString("2021-11-07 03:15:59.000", "America/New_York");
 ```js
 var tzDate = TZ.toUTC("2021-11-07 03:15:59.000", "America/New_York");
 // {
-//   year: 2021, month: 11, day: 7,
+//   year: 2021, month: 10, day: 7,
 //   hour: 3, minute: 15, second: 59, millisecond: 0,
 //   offset: -300, timeZoneName: "Eastern Standard Time"
 // }
@ -38,7 +40,7 @@ TZ.toTimeZoneISOString("2021-03-14T07:15:59.000Z", "America/New_York");
 ```js
 var utcDate = TZ.toTimeZone("2021-03-14T07:15:59.000Z", "America/New_York");
 // {
-//   year: 2021, month: 3, day: 14,
+//   year: 2021, month: 2, day: 14,
 //   hour: 3, minute: 15, second: 59, millisecond: 0,
 //   offset: -240, timeZoneName: "Eastern Daylight Time"
 // }
@ -50,15 +52,26 @@ utcDate.toISOString();

 # Features

-   [x] Translate a UTC time to a Time Zone
-   [x] Translate a Zoned time to UTC
-   [x] Handles **Daylight Savings**, Weird Time Zones, etc...
-   [x] Lightweight (No deps)
-    -   5kb Source + Comments
-    -   2.5kb Minified
-    -   <1kb `gzip`d
+- [x] Translate a UTC time to a Time Zone
+- [x] Translate a Zoned time to UTC
+- [x] Handles **Daylight Savings**, Weird Time Zones, etc...
+  - [x] Well-tested `npm run test`
+- [x] Lightweight (No deps)
+  - 5kb Source + Comments
+  - 2.5kb Minified
+  - <1kb `gzip`d

-Compatible with Node.js & Browsers.
+Compatible with Browsers, and Node.js.
+
+## Browsers
+
+```html
+<script src="https://unpkg.com/xtz@latest/xtz.min.js"></script>
+```
+
+```js
+var TZ = window.XTZ;
+```

 ## Node.js & Webpack

@ -70,28 +83,22 @@ npm install --save xtz
 var TZ = require("xtz");
 ```

-## Browsers
+## Demo

-```html
-<script src="https://unpkg.com/xtz@1.0.0-rc.1/xtz.min.js"></script>
-```
-
-```js
-var TZ = window.XTZ;
-```
+See <https://therootcompany.github.io/tz.js/>.

 # API

-   `toTimeZone(utcDate, timeZone)`
-   `toTimeZoneISOString(isoString, timeZone)`
-   `toUTC(dtString, timeZone)`
-   `toUTCISOString(dtString, timeZone)`
+- `toTimeZone(utcDate, timeZone)`
+- `toTimeZoneISOString(isoString, timeZone)`
+- `toUTC(dtString, timeZone)`
+- `toUTCISOString(dtString, timeZone)`

 ## `toTimeZone(utcDate, timeZone)`

 > Convert UTC into a Target Time Zone

-Use ISO timestamps representing the absolute UTC time in the target time zone:
+Use ISO timestamps representing the absolute UTC time (with or without offset):

 ```txt
 "2021-11-07T08:15:59.000Z"
@ -114,8 +121,8 @@ You can also use a date object with an absolute UTC time:

 ```js
 var tzDate = TZ.toTimeZone(
-    new Date("2021-11-07T08:15:59.000Z"),
-    "America/New_York"
+  new Date("2021-11-07T08:15:59.000Z"),
+  "America/New_York"
 );
 ```

@ -138,7 +145,7 @@ new Date("2021-11-07T03:15:59.000-0500").toISOString());
 Use ISO-like timestamps representing the _local_ time in the target time zone:

 ```txt
-"2021-11-0 T03:15:59.000"
+"2021-11-0 03:15:59.000"
 ```

 Convert directly to an offset ISO String:
@ -154,12 +161,13 @@ Or our bespoke date object:
 var utcDate = TZ.toUTC("2021-11-07 03:15:59.000", "America/New_York");
 ```

-You can also use a date object as the source time, but the date's UTC time will be treated as **_relative to time zone_** rather than absolute (this is a workaround for JavaScript's lack of bi-directional timezone support).
+You can also use a date object as the source time, but the date's UTC time will be treated as **_relative to time
+zone_** rather than absolute (this is a workaround for JavaScript's lack of bi-directional timezone support).

 ```js
 var utcDate = TZ.toUTC(
-    new Date("2021-11-07T03:15:59.000Z"),
-    "America/New_York"
+  new Date("2021-11-07T03:15:59.000Z"),
+  "America/New_York"
 );
 ```

@ -172,30 +180,32 @@ utcDate.toISOString();

 > In 2021 Daylight Savings (in the US)
 >
-> -   begins at 2am on March 14th
-> -   ends at 2am on November 7th
+> - begins at 2am on March 14th (skips to 3am)
+> - ends at 2am on November 7th (resets to 1am)
 >
 > See <https://www.timeanddate.com/time/change/usa>.

 Q: What happens in March when 2am is skipped?

-   A: Although 2am is not a valid time, rather than throwing an error this library will resolve to 1am instead, which is an hour early in real ("tick-tock" or "monotonic") time.
-    ```js
-    var utcDate = TZ.toUTC("2021-03-14 02:15:59.000", "America/New_York");
-    utcDate.toISOString();
-    // "2021-03-14T02:15:59.000-0400"
-    // (same as "2021-03-14T01:15:59.000-0500")
-    ```
+- A: Although 2am is not a valid time, rather than throwing an error this library will resolve to 1am instead, which
+  is an hour early in real ("tick-tock" or "monotonic") time.
+  ```js
+  var utcDate = TZ.toUTC("2021-03-14 02:15:59.000", "America/New_York");
+  utcDate.toISOString();
+  // "2021-03-14T02:15:59.000-0400"
+  // (same as "2021-03-14T01:15:59.000-0500")
+  ```

-Q: What happens in November when 2am happens twice?
+Q: What happens in November when 1am happens twice?

-   A: Although both 2ams are distinguishable with ISO offset times, only the first can be resolved from a local time with this library.
-    ```js
-    var utcDate = TZ.toUTC("2021-11-07 01:15:59.000", "America/New_York");
-    utcDate.toISOString();
-    // "2021-11-07T01:15:59.000-0400", same as "2021-11-07T05:15:59.000Z"
-    // (an hour before the 2nd 2am at "2021-11-07T01:15:59.000-0500")
-    ```
+- A: Although both 1ams are distinguishable with ISO offset times, only the first can be resolved from a local time
+  with this library.
+  ```js
+  var utcDate = TZ.toUTC("2021-11-07 01:15:59.000", "America/New_York");
+  utcDate.toISOString();
+  // "2021-11-07T01:15:59.000-0400", same as "2021-11-07T05:15:59.000Z"
+  // (an hour before the 2nd 1am at "2021-11-07T01:15:59.000-0500")
+  ```

 # List of Time Zones

--- a/examples.js
+++ b/examples.js
@ -1,89 +1,81 @@
 var XTZ;

 (function () {
-    "use strict";
+  "use strict";

-    if (!XTZ) {
-        try {
-            XTZ = require("xtz");
-        } catch (e) {
-            XTZ = require("./xtz.js");
-        }
+  if (!XTZ) {
+    try {
+      XTZ = require("xtz");
+    } catch (e) {
+      XTZ = require("./xtz.js");
    }
+  }

-    var TZ = XTZ;
-    var tzDate;
+  var TZ = XTZ;
+  var tzDate;

-    //
-    // UTC-absolute time translated to a Time Zone
-    //
-    function demo1() {
-        console.info("What's the UTC equivalent of 8:15am in New York?");
-        console.info();
+  //
+  // UTC-absolute time translated to a Time Zone
+  //
+  function demo1() {
+    console.info("What's the UTC equivalent of 8:15am in New York?");
+    console.info();

-        console.info("\t// during daylight savings");
-        console.info(
-            `\tXTZ.toUTC("2021-03-14 08:15:59.000", "America/New_York")`
-        );
-        console.info(`\ttzDate.toISOString()`);
-        tzDate = XTZ.toUTC("2021-03-14 08:15:59.000", "America/New_York");
-        console.info(
-            "\t" + tzDate.toISOString(),
-            "// same as",
-            new Date(tzDate.toISOString()).toISOString()
-        );
-        console.info();
+    console.info("\t// during daylight savings");
+    console.info(`\tXTZ.toUTC("2021-03-14 08:15:59.000", "America/New_York")`);
+    console.info(`\ttzDate.toISOString()`);
+    tzDate = XTZ.toUTC("2021-03-14 08:15:59.000", "America/New_York");
+    console.info(
+      "\t" + tzDate.toISOString(),
+      "// same as",
+      new Date(tzDate.toISOString()).toISOString()
+    );
+    console.info();

-        console.info("\t// during standard time");
-        console.info(
-            `\tXTZ.toUTC("2021-11-07 08:15:59.000", "America/New_York")`
-        );
-        console.info(`\ttzDate.toISOString()`);
-        tzDate = XTZ.toUTC("2021-11-07 08:15:59.000", "America/New_York");
-        console.info(
-            "\t" + tzDate.toISOString(),
-            "// same as",
-            new Date(tzDate.toISOString()).toISOString()
-        );
-        console.info();
-    }
+    console.info("\t// during standard time");
+    console.info(`\tXTZ.toUTC("2021-11-07 08:15:59.000", "America/New_York")`);
+    console.info(`\ttzDate.toISOString()`);
+    tzDate = XTZ.toUTC("2021-11-07 08:15:59.000", "America/New_York");
+    console.info(
+      "\t" + tzDate.toISOString(),
+      "// same as",
+      new Date(tzDate.toISOString()).toISOString()
+    );
+    console.info();
+  }

-    //
-    // Time Zone-relative time translated to UTC
-    //
-    function demo2() {
-        console.info(
-            "What time is it in New York at 8:15am on March 14th UTC?"
-        );
-        console.info();
+  //
+  // Time Zone-relative time translated to UTC
+  //
+  function demo2() {
+    console.info("What time is it in New York at 8:15am on March 14th UTC?");
+    console.info();

-        console.info("\t// during daylight savings");
-        console.info(
-            `\tXTZ.toTimeZone("2021-03-14T08:15:59.000Z", "America/New_York")`
-        );
-        console.info(`\ttzDate.toISOString()`);
-        tzDate = XTZ.toTimeZone("2021-03-14T08:15:59.000Z", "America/New_York");
-        console.info(
-            "\t" + tzDate.toISOString(),
-            "// same as",
-            new Date(tzDate.toISOString()).toISOString()
-        );
-        console.info();
+    console.info("\t// during daylight savings");
+    console.info(
+      `\tXTZ.toTimeZone("2021-03-14T08:15:59.000Z", "America/New_York")`
+    );
+    console.info(`\ttzDate.toISOString()`);
+    tzDate = XTZ.toTimeZone("2021-03-14T08:15:59.000Z", "America/New_York");
+    console.info(
+      "\t" + tzDate.toISOString(),
+      "// same as",
+      new Date(tzDate.toISOString()).toISOString()
+    );
+    console.info();

-        console.info("\t// during standard time");
-        console.info(
-            `\tXTZ.toUTC("2021-11-07T08:15:59.000Z", "America/New_York")`
-        );
-        console.info(`\ttzDate.toISOString()`);
-        tzDate = XTZ.toUTC("2021-11-07T08:15:59.000Z", "America/New_York");
-        console.info(
-            "\t" + tzDate.toISOString(),
-            "// same as",
-            new Date(tzDate.toISOString()).toISOString()
-        );
-        console.info();
-    }
+    console.info("\t// during standard time");
+    console.info(`\tXTZ.toUTC("2021-11-07T08:15:59.000Z", "America/New_York")`);
+    console.info(`\ttzDate.toISOString()`);
+    tzDate = XTZ.toUTC("2021-11-07T08:15:59.000Z", "America/New_York");
+    console.info(
+      "\t" + tzDate.toISOString(),
+      "// same as",
+      new Date(tzDate.toISOString()).toISOString()
+    );
+    console.info();
+  }

-    demo1();
-    demo2();
+  demo1();
+  demo2();
 })();
--- a/index.html
+++ b/index.html
@ -0,0 +1,175 @@
+<!DOCTYPE html>
+<html lang="en" class="no-js">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width" />
+
+    <title>Convert TimeZones in Your Browser</title>
+
+    <link rel="canonical" href="https://therootcompany.github.io/tz.js/" />
+
+    <meta name="theme-color" content="#FF00FF" />
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/spcss@0.7.0" />
+
+    <style>
+      input {
+        width: 24em;
+      }
+    </style>
+  </head>
+
+  <body>
+    <!-- Content -->
+    <h1>
+      <a href="https://github.com/therootcompany/tz.js" target="_blank"
+        >XTZ.js</a
+      >
+    </h1>
+
+    <h3>
+      Current Time:
+      <br />
+      <span class="js-my-dt">YYYY-MM-DDThh:mm:ss.mmm+0000</span>
+    </h3>
+    Current Time Zone: <span class="js-my-tz">America/XXXX</span>
+    <br />
+    Current Time Offset: <span class="js-my-offset">-0000</span>
+    <hr />
+
+    <form class="js-tz2utc">
+      <h3>Relative TimeZone to Absolute UTC:</h3>
+      <label>
+        Time:
+        <input
+          class="js-dt-tz"
+          type="text"
+          placeholder="ex: 2021-03-14 03:15:69.000"
+          required
+        />
+      </label>
+      <br />
+
+      <label>
+        Zone:
+        <input
+          class="js-tz-tz"
+          type="text"
+          placeholder="ex: America/New_York"
+          required
+        />
+      </label>
+      <br />
+      <label>
+        ISO:
+        <input class="js-my-dt-tz" type="text" disabled />
+      </label>
+      <br />
+      <br />
+      <button type="submit">Convert to UTC!</button>
+      <br />
+    </form>
+
+    <hr />
+
+    <form class="js-utc2tz">
+      <h3>Absolute UTC to Relative TimeZone</h3>
+      <label>
+        Time:
+        <input
+          class="js-dt-utc"
+          type="text"
+          placeholder="ex: 2021-03-14 03:15:69.000"
+          required
+        />
+      </label>
+      <br />
+      <label>
+        Zone:
+        <input
+          class="js-tz-utc"
+          type="text"
+          placeholder="ex: America/New_York"
+          required
+        />
+      </label>
+      <br />
+      <label>
+        ISO:
+        <input class="js-my-dt-utc" type="text" disabled />
+      </label>
+      <br />
+      <br />
+      <button type="submit">Convert to TZ!</button>
+      <br />
+    </form>
+
+    <hr />
+    <h3>Time Zones List</h3>
+    See the
+    <a href="https://en.wikipedia.org/wiki/List_of_tz_database_time_zones"
+      >Full List of Time Zones</a
+    >
+    on Wikipedia.
+    <pre>
+America/New_York    -0500 -0400             (Eastern Time)
+America/Denver      -0700 -0600             (Mountain Time)
+America/Phoenix     -0700 (No DST)          (Arizona Time)
+America/Los_Angeles -0800 -0700             (Pacific Time)
+Australia/Adelaide  +0930 +1030    (30-min)
+Asia/Kathmandu      +0545 (No DST) (45-min)
+Asia/Kolkata        +0530 (No DST) (30-min)</pre
+    >
+    <hr />
+    Code at
+    <a href="https://github.com/therootcompany/tz.js" target="_blank"
+      >github.com/therootcompany/tz.js</a
+    >
+    <script src="./xtz.js"></script>
+    <script>
+      function $(sel, el) {
+        return (el || document.body).querySelector(sel);
+      }
+
+      function toUTC() {
+        var curDt = $(".js-dt-tz").value;
+        var curTz = $(".js-tz-tz").value;
+        $(".js-my-dt-tz").value = XTZ.toUTC(curDt, curTz).toISOString();
+      }
+
+      function toTZ() {
+        var curDt = $(".js-dt-utc").value;
+        var curTz = $(".js-tz-utc").value;
+        $(".js-my-dt-utc").value = XTZ.toTimeZone(curDt, curTz).toISOString();
+      }
+
+      var myTz = new Intl.DateTimeFormat("default", {}).resolvedOptions()
+        .timeZone;
+      $(".js-my-tz").innerText = myTz;
+      $(".js-tz-tz").value = myTz;
+      $(".js-tz-utc").value = myTz;
+      $(".js-my-offset").innerText = -1 * new Date().getTimezoneOffset();
+
+      var myDate = new Date();
+      $(".js-my-dt").innerText = XTZ.toTimeZone(myDate, myTz).toISOString();
+      $(".js-dt-tz").value = XTZ.toTimeZone(myDate, myTz)
+        .toISOString()
+        .replace("T", " ")
+        .replace(/(Z|(\+|-)\d+)$/, "");
+      $(".js-dt-utc").value = myDate.toISOString();
+
+      $("form.js-utc2tz").addEventListener("submit", function (ev) {
+        ev.preventDefault();
+        ev.stopPropagation();
+        toTZ();
+      });
+      $("form.js-tz2utc").addEventListener("submit", function (ev) {
+        ev.preventDefault();
+        ev.stopPropagation();
+        toUTC();
+      });
+
+      toUTC();
+      toTZ();
+    </script>
+  </body>
+</html>
--- a/package.json
+++ b/package.json
@ -1,10 +1,11 @@
 {
  "name": "xtz",
-  "version": "1.0.0",
+  "version": "1.0.1",
  "description": "A fast, lightweight, zero-dependency library to translate between Time Zones and UTC with native Intl.DateTimeFormat in ~100 LoC. For Node.js & Browsers.",
  "main": "xtz.js",
  "scripts": {
-    "test": "node ./test.js"
+    "test": "node ./test.js",
+    "build": "uglifyjs ./xtz.js > ./xtz.min.js ; gzip -k -f ./xtz.min.js"
  },
  "repository": {
    "type": "git",
--- a/test.js
+++ b/test.js
@ -3,314 +3,314 @@
 var TZ = require("./");

 function testUtcToTz(t) {
-    var result = TZ.toTimeZone.apply(TZ, t.inputs).toISOString();
-    if (t.result !== result) {
-        throw new Error(
-            `Invalid UTC to TZ conversion for ${t.desc}:\n` +
-                `\tExpected: ${t.result}\n` +
-                `\tActual: ${result}\n`
-        );
-    }
+  var result = TZ.toTimeZone.apply(TZ, t.inputs).toISOString();
+  if (t.result !== result) {
+    throw new Error(
+      `Invalid UTC to TZ conversion for ${t.desc}:\n` +
+        `\tExpected: ${t.result}\n` +
+        `\tActual: ${result}\n`
+    );
+  }
 }

 function testTzToUtc(t) {
-    var result = TZ.toUTC.apply(TZ, t.inputs);
-    if (t.result !== result.toISOString()) {
-        console.log(result);
-        throw new Error(
-            `Invalid TZ to UTC conversion for ${t.desc}:\n` +
-                `\tExpected: ${t.result}\n` +
-                `\tActual: ${result.toISOString()}\n`
-        );
-    }
+  var result = TZ.toUTC.apply(TZ, t.inputs);
+  if (t.result !== result.toISOString()) {
+    console.log(result);
+    throw new Error(
+      `Invalid TZ to UTC conversion for ${t.desc}:\n` +
+        `\tExpected: ${t.result}\n` +
+        `\tActual: ${result.toISOString()}\n`
+    );
+  }
 }

 // At this real UTC time, what does the timezone translate it to?
 [
-    //
-    // Start-of-DST Tests
-    //
+  //
+  // Start-of-DST Tests
+  //

-    // [Start]
-    // What time is '2021-03-14 01:15:59.000 in New York' in UTC? // 2021-03-14 06:15:59.000
-    //                                                            // 2021-03-14T01:15:59.000-0500
-    // What time is '2021-03-14 02:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
-    //                                                            // 2021-03-14T03:15:59.000-0400
-    // What time is '2021-03-14 03:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
-    //                                                            // 2021-03-14T03:15:59.000-0400
-    // What time is '2021-03-14 04:15:59.000 in New York' in UTC? // 2021-03-14 08:15:59.000
-    //                                                            // 2021-03-14T04:15:59.000-0400
-    // [End]
+  // [Start]
+  // What time is '2021-03-14 01:15:59.000 in New York' in UTC? // 2021-03-14 06:15:59.000
+  //                                                            // 2021-03-14T01:15:59.000-0500
+  // What time is '2021-03-14 02:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
+  //                                                            // 2021-03-14T03:15:59.000-0400
+  // What time is '2021-03-14 03:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
+  //                                                            // 2021-03-14T03:15:59.000-0400
+  // What time is '2021-03-14 04:15:59.000 in New York' in UTC? // 2021-03-14 08:15:59.000
+  //                                                            // 2021-03-14T04:15:59.000-0400
+  // [End]

-    // 12:15am NY -0500 => -0400
-    {
-        desc: "UTC to 12:15am NY EST",
-        inputs: ["2021-03-14T05:15:59.000Z", "America/New_York"],
-        result: "2021-03-14T00:15:59.000-0500",
-    },
-    {
-        desc: "UTC to 12:15am NY EST (2)",
-        inputs: ["2021-03-14T00:15:59.000-0500", "America/New_York"],
-        result: "2021-03-14T00:15:59.000-0500",
-    },
-    // 1:15am NY (non-DST)
-    {
-        desc: "UTC to 1:15am NY EST",
-        inputs: ["2021-03-14T06:15:59.000Z", "America/New_York"],
-        result: "2021-03-14T01:15:59.000-0500",
-    },
-    {
-        desc: "UTC to 1:15am NY EST (2)",
-        inputs: ["2021-03-14T01:15:59.000-0500", "America/New_York"],
-        result: "2021-03-14T01:15:59.000-0500",
-    },
+  // 12:15am NY -0500 => -0400
+  {
+    desc: "UTC to 12:15am NY EST",
+    inputs: ["2021-03-14T05:15:59.000Z", "America/New_York"],
+    result: "2021-03-14T00:15:59.000-0500",
+  },
+  {
+    desc: "UTC to 12:15am NY EST (2)",
+    inputs: ["2021-03-14T00:15:59.000-0500", "America/New_York"],
+    result: "2021-03-14T00:15:59.000-0500",
+  },
+  // 1:15am NY (non-DST)
+  {
+    desc: "UTC to 1:15am NY EST",
+    inputs: ["2021-03-14T06:15:59.000Z", "America/New_York"],
+    result: "2021-03-14T01:15:59.000-0500",
+  },
+  {
+    desc: "UTC to 1:15am NY EST (2)",
+    inputs: ["2021-03-14T01:15:59.000-0500", "America/New_York"],
+    result: "2021-03-14T01:15:59.000-0500",
+  },

-    // NOTE: Can't 2:15am NY, because it does not exist (skipped by DST)
+  // NOTE: Can't 2:15am NY, because it does not exist (skipped by DST)

-    // 3:15am NY (DST)
-    {
-        desc: "UTC to 3:15am NY EDT",
-        inputs: ["2021-03-14T07:15:59.000Z", "America/New_York"],
-        result: "2021-03-14T03:15:59.000-0400",
-    },
-    {
-        desc: "UTC to 3:15am NY EDT (2)",
-        inputs: ["2021-03-14T03:15:59.000-0400", "America/New_York"],
-        result: "2021-03-14T03:15:59.000-0400",
-    },
-    // 4:15am NY
-    {
-        desc: "UTC to 4:15am NY EDT",
-        inputs: ["2021-03-14T08:15:59.000Z", "America/New_York"],
-        result: "2021-03-14T04:15:59.000-0400",
-    },
-    {
-        desc: "UTC to 4:15am NY EDT (2)",
-        inputs: ["2021-03-14T04:15:59.000-0400", "America/New_York"],
-        result: "2021-03-14T04:15:59.000-0400",
-    },
+  // 3:15am NY (DST)
+  {
+    desc: "UTC to 3:15am NY EDT",
+    inputs: ["2021-03-14T07:15:59.000Z", "America/New_York"],
+    result: "2021-03-14T03:15:59.000-0400",
+  },
+  {
+    desc: "UTC to 3:15am NY EDT (2)",
+    inputs: ["2021-03-14T03:15:59.000-0400", "America/New_York"],
+    result: "2021-03-14T03:15:59.000-0400",
+  },
+  // 4:15am NY
+  {
+    desc: "UTC to 4:15am NY EDT",
+    inputs: ["2021-03-14T08:15:59.000Z", "America/New_York"],
+    result: "2021-03-14T04:15:59.000-0400",
+  },
+  {
+    desc: "UTC to 4:15am NY EDT (2)",
+    inputs: ["2021-03-14T04:15:59.000-0400", "America/New_York"],
+    result: "2021-03-14T04:15:59.000-0400",
+  },

-    //
-    // End-of-DST Tests
-    //
+  //
+  // End-of-DST Tests
+  //

-    // [Start]
-    // What time is '2021-11-07 01:15:59.000 in New York' in UTC? // 2021-11-07 05:15:59.000
-    //                                                            // 2021-11-07T01:15:59.000-0400
-    //                                                            // 2021-11-07 06:15:59.000
-    //                                                            // 2021-11-07T01:15:59.000-0500
-    // What time is '2021-11-07 02:15:59.000 in New York' in UTC? // 2021-11-07 07:15:59.000
-    //                                                            // 2021-11-07T02:15:59.000-0500
-    // What time is '2021-11-07 03:15:59.000 in New York' in UTC? // 2021-11-07 08:15:59.000
-    // [End]
+  // [Start]
+  // What time is '2021-11-07 01:15:59.000 in New York' in UTC? // 2021-11-07 05:15:59.000
+  //                                                            // 2021-11-07T01:15:59.000-0400
+  //                                                            // 2021-11-07 06:15:59.000
+  //                                                            // 2021-11-07T01:15:59.000-0500
+  // What time is '2021-11-07 02:15:59.000 in New York' in UTC? // 2021-11-07 07:15:59.000
+  //                                                            // 2021-11-07T02:15:59.000-0500
+  // What time is '2021-11-07 03:15:59.000 in New York' in UTC? // 2021-11-07 08:15:59.000
+  // [End]

-    // 12:15am NY -0400 => -0500
-    {
-        desc: "UTC to 2021 Nov 7, 12:15am NY EDT",
-        inputs: ["2021-11-07T04:15:59.000Z", "America/New_York"],
-        result: "2021-11-07T00:15:59.000-0400",
-    },
-    {
-        desc: "UTC to 2021 Nov 7, 12:15am NY EDT (2)",
-        inputs: ["2021-11-07T00:15:59.000-0400", "America/New_York"],
-        result: "2021-11-07T00:15:59.000-0400",
-    },
-    // 1:15am NY (DST) -0400
-    // NOTE: 1:15am happens TWICE (with different offsets)
-    {
-        desc: "UTC to 2021 Nov 7, 1:15am NY EDT",
-        inputs: ["2021-11-07T05:15:59.000Z", "America/New_York"],
-        result: "2021-11-07T01:15:59.000-0400",
-    },
-    {
-        desc: "UTC to 2021 Nov 7, 1:15am NY EDT (2)",
-        inputs: ["2021-11-07T01:15:59.000-0400", "America/New_York"],
-        result: "2021-11-07T01:15:59.000-0400",
-    },
-    // 1:15am NY (non-DST) -0500
-    {
-        desc: "UTC to 2021 Nov 7, 1:15am NY EST",
-        inputs: ["2021-11-07T06:15:59.000Z", "America/New_York"],
-        result: "2021-11-07T01:15:59.000-0500",
-    },
-    {
-        desc: "UTC to 2021 Nov 7, 1:15am NY EST (2)",
-        inputs: ["2021-11-07T01:15:59.000-0500", "America/New_York"],
-        result: "2021-11-07T01:15:59.000-0500",
-    },
-    // 2:15am NY -0500
-    {
-        desc: "UTC to 2021 Nov 7, 2:15am NY EST",
-        inputs: ["2021-11-07T07:15:59.000Z", "America/New_York"],
-        result: "2021-11-07T02:15:59.000-0500",
-    },
-    {
-        desc: "UTC to 2021 Nov 7, 2:15am NY EST (2)",
-        inputs: ["2021-11-07T02:15:59.000-0500", "America/New_York"],
-        result: "2021-11-07T02:15:59.000-0500",
-    },
-    // 3:15am NY
-    {
-        desc: "UTC to 2021 Nov 7, 3:15am NY EST",
-        inputs: ["2021-11-07T08:15:59.000Z", "America/New_York"],
-        result: "2021-11-07T03:15:59.000-0500",
-    },
-    {
-        desc: "UTC to 2021 Nov 7, 3:15am NY EST (2)",
-        inputs: ["2021-11-07T03:15:59.000-0500", "America/New_York"],
-        result: "2021-11-07T03:15:59.000-0500",
-    },
+  // 12:15am NY -0400 => -0500
+  {
+    desc: "UTC to 2021 Nov 7, 12:15am NY EDT",
+    inputs: ["2021-11-07T04:15:59.000Z", "America/New_York"],
+    result: "2021-11-07T00:15:59.000-0400",
+  },
+  {
+    desc: "UTC to 2021 Nov 7, 12:15am NY EDT (2)",
+    inputs: ["2021-11-07T00:15:59.000-0400", "America/New_York"],
+    result: "2021-11-07T00:15:59.000-0400",
+  },
+  // 1:15am NY (DST) -0400
+  // NOTE: 1:15am happens TWICE (with different offsets)
+  {
+    desc: "UTC to 2021 Nov 7, 1:15am NY EDT",
+    inputs: ["2021-11-07T05:15:59.000Z", "America/New_York"],
+    result: "2021-11-07T01:15:59.000-0400",
+  },
+  {
+    desc: "UTC to 2021 Nov 7, 1:15am NY EDT (2)",
+    inputs: ["2021-11-07T01:15:59.000-0400", "America/New_York"],
+    result: "2021-11-07T01:15:59.000-0400",
+  },
+  // 1:15am NY (non-DST) -0500
+  {
+    desc: "UTC to 2021 Nov 7, 1:15am NY EST",
+    inputs: ["2021-11-07T06:15:59.000Z", "America/New_York"],
+    result: "2021-11-07T01:15:59.000-0500",
+  },
+  {
+    desc: "UTC to 2021 Nov 7, 1:15am NY EST (2)",
+    inputs: ["2021-11-07T01:15:59.000-0500", "America/New_York"],
+    result: "2021-11-07T01:15:59.000-0500",
+  },
+  // 2:15am NY -0500
+  {
+    desc: "UTC to 2021 Nov 7, 2:15am NY EST",
+    inputs: ["2021-11-07T07:15:59.000Z", "America/New_York"],
+    result: "2021-11-07T02:15:59.000-0500",
+  },
+  {
+    desc: "UTC to 2021 Nov 7, 2:15am NY EST (2)",
+    inputs: ["2021-11-07T02:15:59.000-0500", "America/New_York"],
+    result: "2021-11-07T02:15:59.000-0500",
+  },
+  // 3:15am NY
+  {
+    desc: "UTC to 2021 Nov 7, 3:15am NY EST",
+    inputs: ["2021-11-07T08:15:59.000Z", "America/New_York"],
+    result: "2021-11-07T03:15:59.000-0500",
+  },
+  {
+    desc: "UTC to 2021 Nov 7, 3:15am NY EST (2)",
+    inputs: ["2021-11-07T03:15:59.000-0500", "America/New_York"],
+    result: "2021-11-07T03:15:59.000-0500",
+  },

-    //
-    // Positive Offset Test
-    //
+  //
+  // Positive Offset Test
+  //

-    // Colombo +0530 (not DST)
-    {
-        desc: "UTC to Asia/Colombo (1)",
-        inputs: ["2021-03-14T08:15:59.000Z", "Asia/Colombo"],
-        result: "2021-03-14T13:45:59.000+0530",
-    },
-    {
-        desc: "UTC to Asia/Colombo (2)",
-        inputs: ["2021-03-14T13:45:59.000+0530", "Asia/Colombo"],
-        result: "2021-03-14T13:45:59.000+0530",
-    },
-    {
-        desc: "UTC to Asia/Colombo (3)",
-        inputs: ["2021-11-07T08:15:59.000Z", "Asia/Colombo"],
-        result: "2021-11-07T13:45:59.000+0530",
-    },
-    {
-        desc: "UTC to Asia/Colombo (4)",
-        inputs: ["2021-11-07T13:45:59.000+0530", "Asia/Colombo"],
-        result: "2021-11-07T13:45:59.000+0530",
-    },
+  // Colombo +0530 (not DST)
+  {
+    desc: "UTC to Asia/Colombo (1)",
+    inputs: ["2021-03-14T08:15:59.000Z", "Asia/Colombo"],
+    result: "2021-03-14T13:45:59.000+0530",
+  },
+  {
+    desc: "UTC to Asia/Colombo (2)",
+    inputs: ["2021-03-14T13:45:59.000+0530", "Asia/Colombo"],
+    result: "2021-03-14T13:45:59.000+0530",
+  },
+  {
+    desc: "UTC to Asia/Colombo (3)",
+    inputs: ["2021-11-07T08:15:59.000Z", "Asia/Colombo"],
+    result: "2021-11-07T13:45:59.000+0530",
+  },
+  {
+    desc: "UTC to Asia/Colombo (4)",
+    inputs: ["2021-11-07T13:45:59.000+0530", "Asia/Colombo"],
+    result: "2021-11-07T13:45:59.000+0530",
+  },
 ].forEach(testUtcToTz);
 console.info("Pass: UTC to TZ for America/New_York and Asia/Colombo");

 [
-    //
-    // Start-of-DST Tests
-    //
+  //
+  // Start-of-DST Tests
+  //

-    // [Start]
-    // What time is '2021-03-14 01:15:59.000 in New York' in UTC? // 2021-03-14 06:15:59.000
-    //                                                            // 2021-03-14T01:15:59.000-0500
-    // What time is '2021-03-14 02:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
-    //                                                            // 2021-03-14T03:15:59.000-0400
-    // What time is '2021-03-14 03:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
-    //                                                            // 2021-03-14T03:15:59.000-0400
-    // What time is '2021-03-14 04:15:59.000 in New York' in UTC? // 2021-03-14 08:15:59.000
-    //                                                            // 2021-03-14T04:15:59.000-0400
-    // [End]
+  // [Start]
+  // What time is '2021-03-14 01:15:59.000 in New York' in UTC? // 2021-03-14 06:15:59.000
+  //                                                            // 2021-03-14T01:15:59.000-0500
+  // What time is '2021-03-14 02:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
+  //                                                            // 2021-03-14T03:15:59.000-0400
+  // What time is '2021-03-14 03:15:59.000 in New York' in UTC? // 2021-03-14 07:15:59.000
+  //                                                            // 2021-03-14T03:15:59.000-0400
+  // What time is '2021-03-14 04:15:59.000 in New York' in UTC? // 2021-03-14 08:15:59.000
+  //                                                            // 2021-03-14T04:15:59.000-0400
+  // [End]

-    // 12:15am NY -0500 => -0400
-    {
-        // 2021-03-14T05:15:59.000Z
-        desc: "2021 Mar 14, 12:15am NY EST to UTC",
-        inputs: ["2021-03-14 00:15:59.000", "America/New_York"],
-        result: "2021-03-14T00:15:59.000-0500",
-    },
-    // 1:15am NY (non-DST)
-    {
-        // 2021-03-14T06:15:59.000Z
-        desc: "2021 Mar 14, 1:15am NY EST to UTC",
-        inputs: ["2021-03-14 01:15:59.000", "America/New_York"],
-        result: "2021-03-14T01:15:59.000-0500",
-    },
+  // 12:15am NY -0500 => -0400
+  {
+    // 2021-03-14T05:15:59.000Z
+    desc: "2021 Mar 14, 12:15am NY EST to UTC",
+    inputs: ["2021-03-14 00:15:59.000", "America/New_York"],
+    result: "2021-03-14T00:15:59.000-0500",
+  },
+  // 1:15am NY (non-DST)
+  {
+    // 2021-03-14T06:15:59.000Z
+    desc: "2021 Mar 14, 1:15am NY EST to UTC",
+    inputs: ["2021-03-14 01:15:59.000", "America/New_York"],
+    result: "2021-03-14T01:15:59.000-0500",
+  },

-    // NOTE: Can't 2:15am NY, because it does not exist (skipped by DST)
-    // This test is here to document the "undefined" behavior
-    {
-        // Both 2021-03-14T06:15:59.000Z and 2021-03-14T07:15:59.000Z
-        // would be reasonable substitutions, I think
-        desc: "2021 Mar 14, 2:15am NY ExT to UTC",
-        inputs: ["2021-03-14 02:15:59.000", "America/New_York"],
-        //result: "2021-03-14T01:15:59.000-0500", // 2021-03-14T06:15:59.000Z
-        result: "2021-03-14T02:15:59.000-0400", // 2021-03-14T06:15:59.000Z
-        //result: "2021-03-14T02:15:59.000-0500", // 2021-03-14T07:15:59.000Z
-    },
+  // NOTE: Can't 2:15am NY, because it does not exist (skipped by DST)
+  // This test is here to document the "undefined" behavior
+  {
+    // Both 2021-03-14T06:15:59.000Z and 2021-03-14T07:15:59.000Z
+    // would be reasonable substitutions, I think
+    desc: "2021 Mar 14, 2:15am NY ExT to UTC",
+    inputs: ["2021-03-14 02:15:59.000", "America/New_York"],
+    //result: "2021-03-14T01:15:59.000-0500", // 2021-03-14T06:15:59.000Z
+    result: "2021-03-14T02:15:59.000-0400", // 2021-03-14T06:15:59.000Z
+    //result: "2021-03-14T02:15:59.000-0500", // 2021-03-14T07:15:59.000Z
+  },

-    // 3:15am NY (DST)
-    {
-        // 2021-03-14T07:15:59.000Z
-        desc: "2021 Mar 14, 3:15am NY EDT to UTC",
-        inputs: ["2021-03-14 03:15:59.000", "America/New_York"],
-        result: "2021-03-14T03:15:59.000-0400",
-    },
-    // 4:15am NY
-    {
-        // 2021-03-14T08:15:59.000Z
-        desc: "2021 Mar 14, 4:15am NY EDT to UTC",
-        inputs: ["2021-03-14 04:15:59.000", "America/New_York"],
-        result: "2021-03-14T04:15:59.000-0400",
-    },
+  // 3:15am NY (DST)
+  {
+    // 2021-03-14T07:15:59.000Z
+    desc: "2021 Mar 14, 3:15am NY EDT to UTC",
+    inputs: ["2021-03-14 03:15:59.000", "America/New_York"],
+    result: "2021-03-14T03:15:59.000-0400",
+  },
+  // 4:15am NY
+  {
+    // 2021-03-14T08:15:59.000Z
+    desc: "2021 Mar 14, 4:15am NY EDT to UTC",
+    inputs: ["2021-03-14 04:15:59.000", "America/New_York"],
+    result: "2021-03-14T04:15:59.000-0400",
+  },

-    //
-    // End-of-DST Tests
-    //
+  //
+  // End-of-DST Tests
+  //

-    // [Start]
-    // What time is '2021-11-07 01:15:59.000 in New York' in UTC? // 2021-11-07 05:15:59.000
-    //                                                            // 2021-11-07T01:15:59.000-0400
-    //                                                            // 2021-11-07 06:15:59.000
-    //                                                            // 2021-11-07T01:15:59.000-0500
-    // What time is '2021-11-07 02:15:59.000 in New York' in UTC? // 2021-11-07 07:15:59.000
-    //                                                            // 2021-11-07T02:15:59.000-0500
-    // What time is '2021-11-07 03:15:59.000 in New York' in UTC? // 2021-11-07 08:15:59.000
-    // [End]
+  // [Start]
+  // What time is '2021-11-07 01:15:59.000 in New York' in UTC? // 2021-11-07 05:15:59.000
+  //                                                            // 2021-11-07T01:15:59.000-0400
+  //                                                            // 2021-11-07 06:15:59.000
+  //                                                            // 2021-11-07T01:15:59.000-0500
+  // What time is '2021-11-07 02:15:59.000 in New York' in UTC? // 2021-11-07 07:15:59.000
+  //                                                            // 2021-11-07T02:15:59.000-0500
+  // What time is '2021-11-07 03:15:59.000 in New York' in UTC? // 2021-11-07 08:15:59.000
+  // [End]

-    // 12:15am NY -0400 => -0500
-    {
-        // 2021-11-07T04:15:59.000Z
-        desc: "2021 Nov 7, 12:15am NY EDT to UTC",
-        inputs: ["2021-11-07 00:15:59.000", "America/New_York"],
-        result: "2021-11-07T00:15:59.000-0400",
-    },
+  // 12:15am NY -0400 => -0500
+  {
+    // 2021-11-07T04:15:59.000Z
+    desc: "2021 Nov 7, 12:15am NY EDT to UTC",
+    inputs: ["2021-11-07 00:15:59.000", "America/New_York"],
+    result: "2021-11-07T00:15:59.000-0400",
+  },

-    // 1:15am NY (DST) -0400
-    // NOTE: 1:15am happens TWICE (with different offsets), so we skip one
-    {
-        // ==> 2021-11-07T05:15:59.000Z
-        // [Skip] 2021-11-07T06:15:59.000Z
-        desc: "2021 Nov 7, 1:15am NY ExT to UTC",
-        inputs: ["2021-11-07 01:15:59.000", "America/New_York"],
-        result: "2021-11-07T01:15:59.000-0400", // 2021-11-07T05:15:59.000Z
-        //result: "2021-11-07T01:15:59.000-0500", // 2021-11-07T06:15:59.000Z
-    },
+  // 1:15am NY (DST) -0400
+  // NOTE: 1:15am happens TWICE (with different offsets), so we skip one
+  {
+    // ==> 2021-11-07T05:15:59.000Z
+    // [Skip] 2021-11-07T06:15:59.000Z
+    desc: "2021 Nov 7, 1:15am NY ExT to UTC",
+    inputs: ["2021-11-07 01:15:59.000", "America/New_York"],
+    result: "2021-11-07T01:15:59.000-0400", // 2021-11-07T05:15:59.000Z
+    //result: "2021-11-07T01:15:59.000-0500", // 2021-11-07T06:15:59.000Z
+  },

-    // 2:15am NY -0500
-    {
-        // 2021-11-07T07:15:59.000Z
-        desc: "2021 Nov 7, 2:15am NY EST to UTC",
-        inputs: ["2021-11-07 02:15:59.000", "America/New_York"],
-        result: "2021-11-07T02:15:59.000-0500",
-    },
-    // 3:15am NY
-    {
-        // 2021-11-07T08:15:59.000Z
-        desc: "2021 Nov 7, 3:15am NY EST to UTC",
-        inputs: ["2021-11-07 03:15:59.000", "America/New_York"],
-        result: "2021-11-07T03:15:59.000-0500",
-    },
+  // 2:15am NY -0500
+  {
+    // 2021-11-07T07:15:59.000Z
+    desc: "2021 Nov 7, 2:15am NY EST to UTC",
+    inputs: ["2021-11-07 02:15:59.000", "America/New_York"],
+    result: "2021-11-07T02:15:59.000-0500",
+  },
+  // 3:15am NY
+  {
+    // 2021-11-07T08:15:59.000Z
+    desc: "2021 Nov 7, 3:15am NY EST to UTC",
+    inputs: ["2021-11-07 03:15:59.000", "America/New_York"],
+    result: "2021-11-07T03:15:59.000-0500",
+  },

-    //
-    // Positive Offset Test
-    //
+  //
+  // Positive Offset Test
+  //

-    // Colombo +0530 (not DST)
-    {
-        // 2021-03-14T08:15:59.000Z
-        desc: "Asia/Colombo to UTC (1)",
-        inputs: ["2021-03-14 13:45:59.000", "Asia/Colombo"],
-        result: "2021-03-14T13:45:59.000+0530",
-    },
-    {
-        // 2021-03-14T08:15:59.000Z
-        desc: "Asia/Colombo to UTC (2)",
-        inputs: ["2021-11-07 13:45:59.000", "Asia/Colombo"],
-        result: "2021-11-07T13:45:59.000+0530",
-    },
+  // Colombo +0530 (not DST)
+  {
+    // 2021-03-14T08:15:59.000Z
+    desc: "Asia/Colombo to UTC (1)",
+    inputs: ["2021-03-14 13:45:59.000", "Asia/Colombo"],
+    result: "2021-03-14T13:45:59.000+0530",
+  },
+  {
+    // 2021-03-14T08:15:59.000Z
+    desc: "Asia/Colombo to UTC (2)",
+    inputs: ["2021-11-07 13:45:59.000", "Asia/Colombo"],
+    result: "2021-11-07T13:45:59.000+0530",
+  },
 ].forEach(testTzToUtc);
 console.info("Pass: TZ to UTC for America/New_York and Asia/Colombo");
--- a/xtz-preview.png
+++ b/xtz-preview.png
--- a/xtz.js
+++ b/xtz.js
@ -1,182 +1,179 @@
 var XTZ;

 (function () {
-    "use strict";
+  "use strict";

-    function toTimeZone(date, timeZone) {
-        // ISO string or existing date object
-        date = new Date(date);
-        var options = {
-            timeZone: timeZone,
-            year: "numeric",
-            month: "numeric",
-            day: "numeric",
-            hour12: false,
-            hour: "numeric",
-            minute: "numeric",
-            second: "numeric",
-            fractionalSecondDigits: 3,
-        };
-
-        var tzOptions = Object.assign({ timeZoneName: "long" }, options);
-
-        // Every country uses the same year and months, right?
-        var formater = new Intl.DateTimeFormat("default", tzOptions);
-        var parts = formater.formatToParts(date);
-
-        var whole = {};
-        parts.forEach(function (part) {
-            var val = part.value;
-            switch (part.type) {
-                case "literal":
-                    // ignore separators and whitespace characters
-                    return;
-                case "timeZoneName":
-                    // keep as is - it's a string
-                    break;
-                case "month":
-                    // months are 0-indexed for new Date()
-                    val = parseInt(val, 10) - 1;
-                    break;
-                case "hour":
-                    // because sometimes 24 is used instead of 0, make 24 0
-                    val = parseInt(val, 10) % 24;
-                    break;
-                case "fractionalSecond":
-                    // fractionalSecond is a dumb name - should be millisecond
-                    whole.millisecond = parseInt(val, 10);
-                    return;
-                default:
-                    val = parseInt(val, 10);
-            }
-            // whole.month = 0;
-            whole[part.type] = val;
-        });
-
-        whole.timeZone = timeZone;
-        whole.offset = getOffset(date, whole);
-        whole.toISOString = _toOffsetISOString;
-        return whole;
-    }
-
-    function toTimeZoneISOString(date, timeZone) {
-        var whole = toTimeZone(date, timeZone);
-        return toOffsetISOString(whole);
-    }
-
-    function _toOffsetISOString() {
-        return toOffsetISOString(this);
-    }
-
-    function getOffset(utcDate, tzD2) {
-        var tzDate = new Date(toOffsetISOString(tzD2));
-        var diff =
-            Math.round(tzDate.valueOf() - utcDate.valueOf()) / (60 * 1000);
-        return diff;
-    }
-
-    function p2(x) {
-        return String(x).padStart(2, "0");
-    }
-
-    function p3(x) {
-        return String(x).padStart(3, "0");
-    }
-
-    function formatOffset(minutes) {
-        if (!minutes) {
-            return "Z";
-        }
-
-        var h = Math.floor(Math.abs(minutes) / 60);
-        var m = Math.abs(minutes) % 60;
-        var offset = "";
-        if (minutes > 0) {
-            offset = "+";
-        } else if (minutes < 0) {
-            offset = "-";
-        }
-
-        // +0500, -0730
-        return (
-            offset +
-            h.toString().padStart(2, "0") +
-            m.toString().padStart(2, "0")
-        );
-    }
-
-    function toOffsetISOString(d) {
-        var offset = formatOffset(d.offset);
-        return (
-            `${d.year}-${p2(d.month + 1)}-${p2(d.day)}` +
-            `T${p2(d.hour)}:${p2(d.minute)}:${p2(d.second)}.${p3(
-                d.millisecond
-            )}${offset}`
-        );
-    }
-
-    function toUTC(dt, tz) {
-        if ("string" === typeof dt) {
-            // Either of these formats should work:
-            // 2021-03-14 01:15:59
-            // 2021-03-14T01:15:59Z
-            dt = dt
-                .replace("T", " ")
-                .replace("Z", "")
-                .replace(" ", "T")
-                .replace(/$/, "Z");
-        }
-        var utcDate = new Date(dt);
-        var tzD2 = toTimeZone(utcDate, tz);
-        var offset = tzD2.offset;
-        tzD2.offset = "";
-
-        var deltaDate = new Date(utcDate);
-        deltaDate.setUTCMinutes(deltaDate.getUTCMinutes() - offset);
-        var tzD3 = toTimeZone(deltaDate, tz);
-
-        if (
-            tzD3.hour === utcDate.getUTCHours() &&
-            tzD3.minute === utcDate.getUTCMinutes()
-        ) {
-            return tzD3;
-        }
-
-        var diff = tzD3.offset - offset;
-        var h = Math.floor(Math.abs(diff) / 60);
-        var m = Math.abs(diff) % 60;
-        var sign = Math.abs(diff) / diff;
-        tzD3.hour -= h * sign;
-        tzD3.minute -= m * sign;
-
-        return tzD3;
-    }
-
-    function toUTCISOString(date, timeZone) {
-        var whole = toUTC(date, timeZone);
-        return toOffsetISOString(whole);
-    }
-
-    XTZ = {
-        // bespoke date =>
-        // 2021-11-07T3:15:59-0500
-        toOffsetISOString: toOffsetISOString,
-
-        // -240 => -0400
-        formatOffset: formatOffset,
-
-        // [ "2021-11-07T08:15:59Z", "America/New_York" ]
-        // => "2021-11-07T03:15:59-0500" // 2021-11-07 03:15:59
-        toTimeZone: toTimeZone,
-        toTimeZoneISOString: toTimeZoneISOString,
-
-        // [ "2021-11-07 03:15:59", "America/New_York" ]
-        // => "2021-11-07T03:15:59-0500" // 2021-11-07T08:15:59Z
-        toUTC: toUTC,
-        toUTCISOString: toUTCISOString,
+  function toTimeZone(date, timeZone) {
+    // ISO string or existing date object
+    date = new Date(date);
+    var options = {
+      timeZone: timeZone,
+      year: "numeric",
+      month: "numeric",
+      day: "numeric",
+      hour12: false,
+      hour: "numeric",
+      minute: "numeric",
+      second: "numeric",
+      fractionalSecondDigits: 3,
    };

-    if ("undefined" != typeof module && module.exports) {
-        module.exports = XTZ;
+    var tzOptions = Object.assign({ timeZoneName: "long" }, options);
+
+    // Every country uses the same year and months, right?
+    var formater = new Intl.DateTimeFormat("default", tzOptions);
+    var parts = formater.formatToParts(date);
+
+    var whole = {};
+    parts.forEach(function (part) {
+      var val = part.value;
+      switch (part.type) {
+        case "literal":
+          // ignore separators and whitespace characters
+          return;
+        case "timeZoneName":
+          // keep as is - it's a string
+          break;
+        case "month":
+          // months are 0-indexed for new Date()
+          val = parseInt(val, 10) - 1;
+          break;
+        case "hour":
+          // because sometimes 24 is used instead of 0, make 24 0
+          val = parseInt(val, 10) % 24;
+          break;
+        case "fractionalSecond":
+          // fractionalSecond is a dumb name - should be millisecond
+          whole.millisecond = parseInt(val, 10);
+          return;
+        default:
+          val = parseInt(val, 10);
+      }
+      // ex: whole.month = 0;
+      whole[part.type] = val;
+    });
+
+    whole.timeZone = timeZone;
+    whole.offset = getOffset(date, whole);
+    whole.toISOString = _toOffsetISOString;
+    return whole;
+  }
+
+  function toTimeZoneISOString(date, timeZone) {
+    var whole = toTimeZone(date, timeZone);
+    return toOffsetISOString(whole);
+  }
+
+  function _toOffsetISOString() {
+    return toOffsetISOString(this);
+  }
+
+  function getOffset(utcDate, tzD2) {
+    var tzDate = new Date(toOffsetISOString(tzD2));
+    var diff = Math.round(tzDate.valueOf() - utcDate.valueOf()) / (60 * 1000);
+    return diff;
+  }
+
+  function p2(x) {
+    return String(x).padStart(2, "0");
+  }
+
+  function p3(x) {
+    return String(x).padStart(3, "0");
+  }
+
+  function formatOffset(minutes) {
+    if (!minutes) {
+      return "Z";
    }
-}());
+
+    var h = Math.floor(Math.abs(minutes) / 60);
+    var m = Math.abs(minutes) % 60;
+    var offset = "";
+    if (minutes > 0) {
+      offset = "+";
+    } else if (minutes < 0) {
+      offset = "-";
+    }
+
+    // +0500, -0730
+    return (
+      offset + h.toString().padStart(2, "0") + m.toString().padStart(2, "0")
+    );
+  }
+
+  function toOffsetISOString(d) {
+    var offset = formatOffset(d.offset);
+    return (
+      `${d.year}-${p2(d.month + 1)}-${p2(d.day)}` +
+      `T${p2(d.hour)}:${p2(d.minute)}:${p2(d.second)}.${p3(
+        d.millisecond
+      )}${offset}`
+    );
+  }
+
+  function toUTC(dt, tz) {
+    if ("string" === typeof dt) {
+      // Either of these formats should work:
+      // 2021-03-14 01:15:59
+      // 2021-03-14T01:15:59Z
+      dt = dt
+        .replace("T", " ")
+        .replace("Z", "")
+        .replace(" ", "T")
+        .replace(/$/, "Z");
+    }
+    var utcDate = new Date(dt);
+    var tzD2 = toTimeZone(utcDate, tz);
+    var offset = tzD2.offset;
+    tzD2.offset = "";
+
+    var deltaDate = new Date(utcDate);
+    deltaDate.setUTCMinutes(deltaDate.getUTCMinutes() - offset);
+    var tzD3 = toTimeZone(deltaDate, tz);
+
+    if (
+      tzD3.hour === utcDate.getUTCHours() &&
+      tzD3.minute === utcDate.getUTCMinutes()
+    ) {
+      return tzD3;
+    }
+
+    var diff = tzD3.offset - offset;
+    var h = Math.floor(Math.abs(diff) / 60);
+    var m = Math.abs(diff) % 60;
+    var sign = Math.abs(diff) / diff;
+    tzD3.hour -= h * sign;
+    tzD3.minute -= m * sign;
+
+    return tzD3;
+  }
+
+  function toUTCISOString(date, timeZone) {
+    var whole = toUTC(date, timeZone);
+    return toOffsetISOString(whole);
+  }
+
+  XTZ = {
+    // bespoke date =>
+    // 2021-11-07T3:15:59-0500
+    toOffsetISOString: toOffsetISOString,
+
+    // -240 => -0400
+    formatOffset: formatOffset,
+
+    // [ "2021-11-07T08:15:59Z", "America/New_York" ]
+    // => "2021-11-07T03:15:59-0500" // 2021-11-07 03:15:59
+    toTimeZone: toTimeZone,
+    toTimeZoneISOString: toTimeZoneISOString,
+
+    // [ "2021-11-07 03:15:59", "America/New_York" ]
+    // => "2021-11-07T03:15:59-0500" // 2021-11-07T08:15:59Z
+    toUTC: toUTC,
+    toUTCISOString: toUTCISOString,
+  };
+
+  if ("undefined" != typeof module && module.exports) {
+    module.exports = XTZ;
+  }
+})();
Author	SHA1	Message	Date
AJ ONeal	5c35bd2148	fix typo, clarify comment	2021-05-28 08:37:35 -06:00
AJ ONeal	8b8af276ef	add build command	2021-05-28 08:28:18 -06:00
AJ ONeal	72f68a10f0	fix bad description	2021-05-28 08:28:01 -06:00
AJ ONeal	4de76c4ccc	fix typo: 2nd 2am => 2nd 1am	2021-05-28 08:08:53 -06:00
AJ ONeal	dea25807e0	make current time copy/paste easier	2021-05-28 02:16:33 -06:00
AJ ONeal	6d6635b838	1.0.1	2021-05-28 02:14:17 -06:00
AJ ONeal	7ea37d8772	typo fix	2021-05-28 02:14:13 -06:00
AJ ONeal	37181d65a0	bugfix: respect updated tz values	2021-05-28 02:09:15 -06:00
AJ ONeal	77300f69b2	add demo link	2021-05-28 02:04:29 -06:00
AJ ONeal	dacf0eaaf2	update docs with demo	2021-05-28 02:03:49 -06:00
AJ ONeal	a0172f68a3	add demo page	2021-05-28 01:55:01 -06:00
AJ ONeal	ff9e266052	make Prettier	2021-05-28 00:57:42 -06:00
AJ ONeal	aaa31a25b9	note tests	2021-05-28 00:51:14 -06:00
AJ ONeal	8ddd8cd2f5	update cdn link, put browser first	2021-05-28 00:42:21 -06:00