Add negative length option to toIsoString(). Add Timezone.version. Trim spurious beginning transition entry. Update to use timezone data generated by @tubular/time-tzdb. (#7)

Author: kshetline

.eslintrc.json

@@ -5,7 +5,6 @@
     "node": true
   },
   "extends": [
-    "standard",
     "plugin:@typescript-eslint/eslint-recommended"
   ],
   "globals": {

README.md

@@ -1125,7 +1125,8 @@ toDate(): Date;
 toHoursAndMinutesString(includeDst = false): string;
 
 // Format as 'Y-MM-DDTHH:mm:ss.SSSZ', trimming to an optional maxLength that *does not* count
-//   any leading + or - sign.
+//   any leading + or - sign. If maxLength is negative, remove that many characters from the
+//   end of the full string. Base length for positive years <= 9999 is 24 characters.
 toIsoString(maxLength?: number): string;
 
 // Create a clone of a DateTime instance with a different locale.
@@ -1168,6 +1169,12 @@ addDaysToDate(deltaDays: number, yearOrDate: YearOrDate, month?: number, day?: n
   static DATELESS: Timezone; // A pseudo timezone for abstract dateless, time-only `DateTime` instances.
 ```
 
+### Static `Timezone` getter
+
+```typescript
+version: string; // Current timezone version, e.g. 2021a
+```
+
 ### Static `Timezone` methods
 
 Check if a given IANA `zoneName` is associated with an ISO Alpha-2 (two-letter) `country` code:

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@tubular/time",
-  "version": "2.4.2",
+  "version": "2.5.0",
   "description": "Date/time, IANA timezones, calendar with settable Julian/Gregorian switchover",
   "browser": "dist/web/index.js",
   "browser-es5": "dist/web5/index.js",
@@ -35,7 +35,7 @@
   "license": "MIT",
   "dependencies": {
     "@tubular/math": "^2.2.1",
-    "@tubular/util": "^3.4.1"
+    "@tubular/util": "^3.5.0"
   },
   "devDependencies": {
     "@babel/core": "^7.13.8",
@@ -50,12 +50,10 @@
     "by-request": "^1.2.0",
     "chai": "^4.2.0",
     "eslint": "^7.21.0",
-    "eslint-config-standard": "^16.0.2",
     "eslint-plugin-chai-friendly": "^0.6.0",
     "eslint-plugin-import": "^2.22.1",
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-promise": "^4.2.1",
-    "eslint-plugin-standard": "^5.0.0",
     "esm": "^3.2.25",
     "mocha": "^8.2.1",
     "nyc": "^15.1.0",

package.json

@@ -1397,7 +1397,9 @@ export class DateTime extends Calendar {
     let s = this.format(undefined, 'en-US');
 
     if (maxLength != null) {
-      if (/^[-+]/.test(s))
+      if (maxLength < 0)
+        maxLength = s.length + maxLength;
+      else if (/^[-+]/.test(s))
         ++maxLength;
 
       s = s.substr(0, maxLength);

src/date-time.ts

@@ -2,6 +2,8 @@ import { expect } from 'chai';
 import { Timezone } from './timezone';
 import timezoneLarge from './timezone-large';
 
+const version = timezoneLarge.version;
+
 describe('Timezone', () => {
   beforeEach(() => Timezone.defineTimezones(Object.assign({
     'America/Barberg': 'America/Chicago',
@@ -10,6 +12,7 @@ describe('Timezone', () => {
 
   it('should properly create Timezone instances', () => {
     expect(Timezone.from('America/New_York').aliasFor).to.equal(null);
+    expect(Timezone.from('Antarctica/Troll').aliasFor).to.equal(null);
     expect(Timezone.from('America/New_York').population).to.be.greaterThan(20000000);
     expect(Timezone.from('America/New_York').supportsCountry('US')).to.be.true;
     expect(Timezone.from('America/New_York').supportsCountry('AD')).to.be.false;
@@ -21,12 +24,13 @@ describe('Timezone', () => {
 
   it('should properly guess matching timezones', () => {
     expect(Timezone.guess(true, 'US', 'US/Eastern')).to.equal('America/New_York');
-    expect(Timezone.guess(true, 'CA', 'US/Eastern')).to.equal('America/Montreal');
+    expect(Timezone.guess(true, 'CA', 'US/Eastern')).to.equal('America/Toronto');
     expect(Timezone.guess(true, 'LY', 'Africa/Cairo')).to.equal('Africa/Tripoli');
     Timezone.guess(true);
   });
 
   it('should properly perform Timezone utility functions', () => {
+    expect(Timezone.version).to.equal(version);
     expect(Timezone.from('America/Fooberg').population).to.equal(250);
     expect(Timezone.getPopulation('America/Fooberg')).to.equal(250);
     expect(Timezone.from('America/Fooberg').supportsCountry('xx')).to.be.true;

src/timezone-large-alt.ts

@@ -193,6 +193,9 @@ export class Timezone {
   private static countriesForZone: Record<string, Set<string>> = {};
   private static zonesForCountry: Record<string, Set<string>> = {};
   private static populationForZone: Record<string, number> = {};
+  private static _version: string = 'unspecified';
+
+  static get version(): string { return this._version; }
 
   static OS_ZONE = new Timezone({ zoneName: 'OS', currentUtcOffset: osProbableStdOffset, usesDst: osUsesDst,
                             dstOffset: osDstOffset, transitions: osTransitions });
@@ -208,7 +211,7 @@ export class Timezone {
 
   private static offsetsAndZones: OffsetsAndZones[];
   private static regionAndSubzones: RegionAndSubzones[];
-  private static zoneLookup: { [id: string]: Timezone } = {};
+  private static zoneLookup: Record<string, Timezone> = {};
 
   private readonly _zoneName: string;
   private readonly _utcOffset: number;
@@ -229,6 +232,11 @@ export class Timezone {
   static defineTimezones(encodedTimezones: Record<string, string>): boolean {
     const changed = !isEqual(this.encodedTimezones, encodedTimezones);
 
+    if (encodedTimezones.version)
+      this._version = encodedTimezones.version;
+    else
+      this._version = 'unspecified';
+
     this.encodedTimezones = Object.assign({}, encodedTimezones ?? {});
     this.extractZoneInfo();
 
@@ -797,6 +805,9 @@ export class Timezone {
                      last(insertTransitions).transitionTime >= transitions[1].transitionTime)
                 insertTransitions.splice(insertTransitions.length - 1, 1);
 
+              if (insertTransitions[0].transitionTime === transitions[0].transitionTime)
+                insertTransitions.splice(0, 1);
+
               transitions.splice(1, 0, ...insertTransitions);
             }
           }