fix: timezone plugin DST error (#1352)

iamkun · Jan 28, 2021 · 71bed15 · 71bed15
1 parent 1138a3f
commit 71bed15
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 5 deletions.
diff --git a/src/plugin/timezone/index.js b/src/plugin/timezone/index.js
@@ -36,8 +36,6 @@ const getDateTimeFormat = (timezone, options = {}) => {
 export default (o, c, d) => {
   let defaultTimezone
 
-  const localUtcOffset = d().utcOffset()
-
   const makeFormatParts = (timestamp, timezone, options = {}) => {
     const date = new Date(timestamp)
     const dtf = getDateTimeFormat(timezone, options)
@@ -96,9 +94,11 @@ export default (o, c, d) => {
 
   proto.tz = function (timezone = defaultTimezone, keepLocalTime) {
     const oldOffset = this.utcOffset()
-    const target = this.toDate().toLocaleString('en-US', { timeZone: timezone })
-    const diff = Math.round((this.toDate() - new Date(target)) / 1000 / 60)
-    let ins = d(target).$set(MS, this.$ms).utcOffset(localUtcOffset - diff, true)
+    const date = this.toDate()
+    const target = date.toLocaleString('en-US', { timeZone: timezone })
+    const diff = Math.round((date - new Date(target)) / 1000 / 60)
+    let ins = d(target).$set(MS, this.$ms)
+      .utcOffset((-Math.round(date.getTimezoneOffset() / 15) * 15) - diff, true)
     if (keepLocalTime) {
       const newOffset = ins.utcOffset()
       ins = ins.add(oldOffset - newOffset, MIN)

diff --git a/test/plugin/timezone.test.js b/test/plugin/timezone.test.js
@@ -101,7 +101,9 @@ describe('Convert', () => {
       const jun = _('2014-06-01T12:00:00Z')
       const dec = _('2014-12-01T12:00:00Z')
       expect(jun.tz('America/Los_Angeles').format('ha')).toBe('5am')
+      expect(jun.tz('America/Los_Angeles').utcOffset()).toBe(-7 * 60)
       expect(dec.tz('America/Los_Angeles').format('ha')).toBe('4am')
+      expect(dec.tz('America/Los_Angeles').utcOffset()).toBe(-8 * 60)
       expect(jun.tz(NY).format('ha')).toBe('8am')
       expect(dec.tz(NY).format('ha')).toBe('7am')
       expect(jun.tz(TOKYO).format('ha')).toBe('9pm')