fix: Add Experimental Timezone Plugin (#974)

.travis.yml

@@ -7,7 +7,6 @@ node_js:
   - '12'
   - '10'
   - '8'
-  - '6'
 install:
   - npm install -g codecov
   - npm install

package.json

@@ -87,6 +87,7 @@
     "karma-sauce-launcher": "^1.1.0",
     "mockdate": "^2.0.2",
     "moment": "2.27.0",
+    "moment-timezone": "0.5.31",
     "ncp": "^2.0.0",
     "pre-commit": "^1.2.2",
     "prettier": "^1.16.1",

src/plugin/timezone/index.js

@@ -0,0 +1,71 @@
+const typeToPos = {
+  year: 0,
+  month: 1,
+  day: 2,
+  hour: 3,
+  minute: 4,
+  second: 5
+}
+
+export default (o, c, d) => {
+  const localUtcOffset = d().utcOffset()
+  const tzOffset = (timestamp, timezone) => {
+    const date = new Date(timestamp)
+    const dtf = new Intl.DateTimeFormat('en-US', {
+      hour12: false,
+      timeZone: timezone,
+      year: 'numeric',
+      month: '2-digit',
+      day: '2-digit',
+      hour: '2-digit',
+      minute: '2-digit',
+      second: '2-digit'
+    })
+    const fotmatResult = dtf.formatToParts(date)
+    const filled = []
+    for (let i = 0; i < fotmatResult.length; i += 1) {
+      const { type, value } = fotmatResult[i]
+      const pos = typeToPos[type]
+
+      if (pos >= 0) {
+        filled[pos] = parseInt(value, 10)
+      }
+    }
+    const utcString = `${filled[0]}-${filled[1]}-${filled[2]} ${filled[3]}:${filled[4]}:${filled[5]}:000`
+    const utcTs = d.utc(utcString).valueOf()
+    let asTS = +date
+    const over = asTS % 1000
+    asTS -= over >= 0 ? over : 1000 + over
+    return (utcTs - asTS) / (60 * 1000)
+  }
+  const fixOffset = (localTS, o0, tz) => {
+    let utcGuess = localTS - (o0 * 60 * 1000)
+    const o2 = tzOffset(utcGuess, tz)
+    if (o0 === o2) {
+      return [utcGuess, o0]
+    }
+    utcGuess -= (o2 - o0) * 60 * 1000
+    const o3 = tzOffset(utcGuess, tz)
+    if (o2 === o3) {
+      return [utcGuess, o2]
+    }
+    return [localTS - (Math.min(o2, o3) * 60 * 1000), Math.max(o2, o3)]
+  }
+  const proto = c.prototype
+  proto.tz = function (timezone) {
+    const target = this.toDate().toLocaleString('en-US', { timeZone: timezone })
+    const diff = (this.toDate() - new Date(target)) / 1000 / 60
+    return d(target).utcOffset(localUtcOffset - diff, true)
+  }
+  d.tz = function (input, timezone) {
+    const previousoffset = tzOffset(+d(), timezone)
+    const localTs = d.utc(input).valueOf()
+    const [targetTs, targetOffset] = fixOffset(localTs, previousoffset, timezone)
+    const ins = d(targetTs).utcOffset(targetOffset)
+    return ins
+  }
+
+  d.tz.guess = function () {
+    return Intl.DateTimeFormat().resolvedOptions().timeZone
+  }
+}

test/plugin/timezone.test.js

@@ -0,0 +1,131 @@
+import MockDate from 'mockdate'
+import moment from 'moment-timezone'
+import dayjs from '../../src'
+import utc from '../../src/plugin/utc'
+import timezone from '../../src/plugin/timezone'
+
+dayjs.extend(utc)
+dayjs.extend(timezone)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+const NY = 'America/New_York'
+
+describe('Guess', () => {
+  it('return string', () => {
+    expect(typeof dayjs.tz.guess()).toBe('string')
+  })
+})
+
+
+describe('Parse', () => {
+  it('parse target time string', () => {
+    const newYork = dayjs.tz('2014-06-01 12:00', NY)
+    const MnewYork = moment.tz('2014-06-01 12:00', NY)
+    expect(newYork.format()).toBe('2014-06-01T12:00:00-04:00')
+    expect(newYork.format()).toBe(MnewYork.format())
+    expect(newYork.utcOffset()).toBe(-240)
+    expect(newYork.utcOffset()).toBe(MnewYork.utcOffset())
+    expect(newYork.valueOf()).toBe(1401638400000)
+    expect(newYork.valueOf()).toBe(MnewYork.valueOf())
+  })
+
+  it('parse and convert between timezones', () => {
+    const newYork = dayjs.tz('2014-06-01 12:00', NY)
+    expect(newYork.tz('America/Los_Angeles').format()).toBe('2014-06-01T09:00:00-07:00')
+    expect(newYork.tz('Europe/London').format()).toBe('2014-06-01T17:00:00+01:00')
+  })
+})
+
+describe('Convert', () => {
+  it('convert to target time', () => {
+    const losAngeles = dayjs('2014-06-01T12:00:00Z').tz('America/Los_Angeles')
+    const MlosAngeles = dayjs('2014-06-01T12:00:00Z').tz('America/Los_Angeles')
+    expect(losAngeles.format()).toBe('2014-06-01T05:00:00-07:00')
+    expect(losAngeles.format()).toBe(MlosAngeles.format())
+    expect(losAngeles.valueOf()).toBe(1401624000000)
+    expect(losAngeles.valueOf()).toBe(MlosAngeles.valueOf())
+    expect(losAngeles.utcOffset()).toBe(-420)
+    expect(losAngeles.utcOffset()).toBe(MlosAngeles.utcOffset())
+  })
+
+  it('convert to target time', () => {
+    const losAngeles = dayjs('2014-06-01T12:00:00Z').tz('America/Los_Angeles')
+    expect(losAngeles.format()).toBe('2014-06-01T05:00:00-07:00')
+    expect(losAngeles.valueOf()).toBe(1401624000000)
+  })
+
+  it('DST', () => {
+    const jun = dayjs('2014-06-01T12:00:00Z')
+    const dec = dayjs('2014-12-01T12:00:00Z')
+
+    expect(jun.tz('America/Los_Angeles').format('ha')).toBe('5am')
+    expect(dec.tz('America/Los_Angeles').format('ha')).toBe('4am')
+    expect(jun.tz(NY).format('ha')).toBe('8am')
+    expect(dec.tz(NY).format('ha')).toBe('7am')
+    expect(jun.tz('Asia/Tokyo').format('ha')).toBe('9pm')
+    expect(dec.tz('Asia/Tokyo').format('ha')).toBe('9pm')
+    expect(jun.tz('Australia/Sydney').format('ha')).toBe('10pm')
+    expect(dec.tz('Australia/Sydney').format('ha')).toBe('11pm')
+  })
+})
+
+
+describe('DST, a time that never existed', () => {
+  // 11 March 2012, 02:00:00 clocks were
+  // turned forward 1 hour to 11 March 2012, 03:00:00 local
+  // daylight time instead.
+  // 02:00 -> 03:00
+  // 02:59 -> 03:59
+
+  it('2012-03-11 01:59:59', () => {
+    const s = '2012-03-11 01:59:59'
+    const d = dayjs.tz(s, NY)
+    const m = moment.tz(s, NY)
+    expect(d.format()).toBe('2012-03-11T01:59:59-05:00')
+    expect(d.format()).toBe(m.format())
+    expect(d.utcOffset()).toBe(-300)
+    expect(d.utcOffset()).toBe(m.utcOffset())
+    expect(d.valueOf()).toBe(1331449199000)
+    expect(d.valueOf()).toBe(m.valueOf())
+  })
+  it('2012-03-11 02:00:00', () => {
+    const s = '2012-03-11 02:00:00'
+    const d = dayjs.tz(s, NY)
+    const m = moment.tz(s, NY)
+    expect(d.format()).toBe('2012-03-11T03:00:00-04:00')
+    expect(d.format()).toBe(m.format())
+    expect(d.valueOf()).toBe(m.valueOf())
+    expect(d.valueOf()).toBe(1331449200000)
+    expect(d.utcOffset()).toBe(-240)
+    expect(d.utcOffset()).toBe(m.utcOffset())
+  })
+  it('2012-03-11 02:59:59', () => {
+    const s = '2012-03-11 02:59:59'
+    const d = dayjs.tz(s, NY)
+    const m = moment.tz(s, NY)
+    expect(d.format()).toBe('2012-03-11T03:59:59-04:00')
+    expect(d.format()).toBe(m.format())
+    expect(d.valueOf()).toBe(m.valueOf())
+    expect(d.valueOf()).toBe(1331452799000)
+    expect(d.utcOffset()).toBe(-240)
+    expect(d.utcOffset()).toBe(m.utcOffset())
+  })
+  it('2012-03-11 03:00:00', () => {
+    const s = '2012-03-11 03:00:00'
+    const d = dayjs.tz(s, NY)
+    const m = moment.tz(s, NY)
+    expect(d.format()).toBe('2012-03-11T03:00:00-04:00')
+    expect(d.format()).toBe(m.format())
+    expect(d.valueOf()).toBe(m.valueOf())
+    expect(d.valueOf()).toBe(1331449200000)
+    expect(d.utcOffset()).toBe(-240)
+    expect(d.utcOffset()).toBe(m.utcOffset())
+  })
+})

types/plugin/timezone.d.ts

@@ -0,0 +1,17 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+interface DayjsTimezone {
+  (): Dayjs
+  guess(): string
+}
+
+declare module 'dayjs' {
+  interface Dayjs {
+    tz(): Dayjs
+  }
+
+  const tz: DayjsTimezone
+}