From 018d293891e38044ed21ed154605caa717fcab45 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Thu, 7 Mar 2019 17:26:07 +0800
Subject: [PATCH 01/17] init setUTCOffset plugin

---
 src/index.js                     |  3 ++-
 src/plugin/setUTCOffset/index.js | 29 +++++++++++++++++++++++++++++
 test/plugin/setUTCOffset.test.js | 28 ++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 src/plugin/setUTCOffset/index.js
 create mode 100644 test/plugin/setUTCOffset.test.js

diff --git a/src/index.js b/src/index.js
index 434f60362..c70291f2f 100644
--- a/src/index.js
+++ b/src/index.js
@@ -38,7 +38,8 @@ const dayjs = (date, c, pl) => {
   return new Dayjs(cfg) // eslint-disable-line no-use-before-define
 }
 
-const wrapper = (date, instance) => dayjs(date, { locale: instance.$L, utc: instance.$u })
+const wrapper = (date, instance) =>
+  dayjs(date, { locale: instance.$L, utc: instance.$u, $offset: instance.$offset })
 
 const Utils = U // for plugin use
 Utils.l = parseLocale
diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
new file mode 100644
index 000000000..6c368888a
--- /dev/null
+++ b/src/plugin/setUTCOffset/index.js
@@ -0,0 +1,29 @@
+export default (option, Dayjs) => {
+  const proto = Dayjs.prototype
+  const oldParse = proto.parse
+  proto.parse = function (cfg) {
+    if (!this.$utils().u(cfg.$offset)) {
+      this.$offset = cfg.$offset
+    }
+    oldParse.call(this, cfg)
+  }
+
+  const oldUtcOffset = proto.utcOffset
+  proto.utcOffset = function (input) {
+    const { u } = this.$utils()
+    if (u(input)) {
+      if (this.$u) {
+        return 0
+      }
+      if (!u(this.$offset)) {
+        return this.$offset
+      }
+      return oldUtcOffset.call(this)
+    }
+    const offset = Math.abs(input) <= 16 ? input * 60 : input
+    this.$offset = offset
+    return this.add(offset + this.$d.getTimezoneOffset(), 'minute')
+  }
+
+  // todo toString valueOf toDate shoud minus back to original date
+}
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
new file mode 100644
index 000000000..8006ec5be
--- /dev/null
+++ b/test/plugin/setUTCOffset.test.js
@@ -0,0 +1,28 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import setUTCOffset from '../../src/plugin/setUTCOffset'
+
+dayjs.extend(setUTCOffset)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('UTC Year', () => {
+  expect(dayjs().utcOffset(540).utcOffset()).toBe(moment().utcOffset(540).utcOffset())
+  expect(dayjs().utcOffset(540).format()).toBe(moment().utcOffset(540).format())
+  expect(dayjs().utcOffset(60).format()).toBe(moment().utcOffset(60).format())
+  expect(dayjs().utcOffset(8).format()).toBe(moment().utcOffset(8).format())
+
+  expect(dayjs().utcOffset(-540).utcOffset()).toBe(moment().utcOffset(-540).utcOffset())
+  expect(dayjs().utcOffset(-540).format()).toBe(moment().utcOffset(-540).format())
+
+  expect(dayjs().utcOffset(-60).format()).toBe(moment().utcOffset(-60).format())
+  expect(dayjs().utcOffset(-8).format()).toBe(moment().utcOffset(-8).format())
+  // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
+})

From 079bec30cec48d17fdd2dae9e9efe8167b678a6c Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 16:01:54 +0800
Subject: [PATCH 02/17] update

---
 test/plugin/setUTCOffset.test.js | 2 +-
 types/plugin/setUtcOffset.d.ts   | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 types/plugin/setUtcOffset.d.ts

diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index 8006ec5be..5ab4b2d04 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -13,7 +13,7 @@ afterEach(() => {
   MockDate.reset()
 })
 
-it('UTC Year', () => {
+it('Set utcOffset -> Get utcOffset', () => {
   expect(dayjs().utcOffset(540).utcOffset()).toBe(moment().utcOffset(540).utcOffset())
   expect(dayjs().utcOffset(540).format()).toBe(moment().utcOffset(540).format())
   expect(dayjs().utcOffset(60).format()).toBe(moment().utcOffset(60).format())
diff --git a/types/plugin/setUtcOffset.d.ts b/types/plugin/setUtcOffset.d.ts
new file mode 100644
index 000000000..30ec75e5d
--- /dev/null
+++ b/types/plugin/setUtcOffset.d.ts
@@ -0,0 +1,4 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin

From 4b3c987977c756d2fad63f151965d16a959d6fb7 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:10:06 +0800
Subject: [PATCH 03/17] update valueOf

---
 src/index.js                     | 4 ++--
 src/plugin/setUTCOffset/index.js | 7 ++++++-
 test/plugin/setUTCOffset.test.js | 4 ++++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/index.js b/src/index.js
index c70291f2f..70c8ecb33 100644
--- a/src/index.js
+++ b/src/index.js
@@ -264,7 +264,7 @@ class Dayjs {
       [C.S]: C.MILLISECONDS_A_SECOND
     }[unit] || 1 // ms
 
-    const nextTimeStamp = this.valueOf() + (number * step)
+    const nextTimeStamp = this.$d.getTime() + (number * step)
     return Utils.w(nextTimeStamp, this)
   }
 
@@ -371,7 +371,7 @@ class Dayjs {
   }
 
   toDate() {
-    return new Date(this.$d)
+    return new Date(this.valueOf())
   }
 
   toJSON() {
diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
index 6c368888a..19ec9a6c7 100644
--- a/src/plugin/setUTCOffset/index.js
+++ b/src/plugin/setUTCOffset/index.js
@@ -1,6 +1,7 @@
 export default (option, Dayjs) => {
   const proto = Dayjs.prototype
   const oldParse = proto.parse
+  const localOffset = (new Date()).getTimezoneOffset()
   proto.parse = function (cfg) {
     if (!this.$utils().u(cfg.$offset)) {
       this.$offset = cfg.$offset
@@ -8,6 +9,10 @@ export default (option, Dayjs) => {
     oldParse.call(this, cfg)
   }
 
+  proto.valueOf = function () {
+    return this.$d.valueOf() - (((this.$offset || 0) + localOffset) * 60000)
+  }
+
   const oldUtcOffset = proto.utcOffset
   proto.utcOffset = function (input) {
     const { u } = this.$utils()
@@ -22,7 +27,7 @@ export default (option, Dayjs) => {
     }
     const offset = Math.abs(input) <= 16 ? input * 60 : input
     this.$offset = offset
-    return this.add(offset + this.$d.getTimezoneOffset(), 'minute')
+    return this.add(offset + localOffset, 'minute')
   }
 
   // todo toString valueOf toDate shoud minus back to original date
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index 5ab4b2d04..26d1ba814 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -26,3 +26,7 @@ it('Set utcOffset -> Get utcOffset', () => {
   expect(dayjs().utcOffset(-8).format()).toBe(moment().utcOffset(-8).format())
   // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
+
+it('Set utcOffset -> Get utcOffset', () => {
+  expect(dayjs().utcOffset(9).valueOf()).toBe(moment().utcOffset(9).valueOf())
+})

From c853382046c9a0adeb25bd1681a472a3a1f9aa87 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:18:34 +0800
Subject: [PATCH 04/17] update valueOf

---
 src/plugin/setUTCOffset/index.js |  3 ++-
 test/plugin/setUTCOffset.test.js | 10 ++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
index 19ec9a6c7..9cd015cb0 100644
--- a/src/plugin/setUTCOffset/index.js
+++ b/src/plugin/setUTCOffset/index.js
@@ -10,7 +10,8 @@ export default (option, Dayjs) => {
   }
 
   proto.valueOf = function () {
-    return this.$d.valueOf() - (((this.$offset || 0) + localOffset) * 60000)
+    const addedOffset = !this.$utils().u(this.$offset) ? (this.$offset || 0) + localOffset : 0
+    return this.$d.valueOf() - (addedOffset * 60000)
   }
 
   const oldUtcOffset = proto.utcOffset
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index 26d1ba814..77d6219bc 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -27,6 +27,12 @@ it('Set utcOffset -> Get utcOffset', () => {
   // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
 
-it('Set utcOffset -> Get utcOffset', () => {
-  expect(dayjs().utcOffset(9).valueOf()).toBe(moment().utcOffset(9).valueOf())
+it('valueOf should be the same as original', () => {
+  const d = dayjs()
+  const du = dayjs().utcOffset(9)
+  const m = moment()
+  const mu = moment().utcOffset(9)
+  expect(d.valueOf()).toBe(m.valueOf())
+  expect(d.valueOf()).toBe(du.valueOf())
+  expect(du.valueOf()).toBe(mu.valueOf())
 })

From b5ce204cc0d497af09b398cf43bed7b6eb71e576 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:20:41 +0800
Subject: [PATCH 05/17] update todate

---
 test/plugin/setUTCOffset.test.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index 77d6219bc..5172f2cca 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -27,12 +27,12 @@ it('Set utcOffset -> Get utcOffset', () => {
   // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
 
-it('valueOf should be the same as original', () => {
+it('valueOf, toDate should be the same as original', () => {
   const d = dayjs()
   const du = dayjs().utcOffset(9)
-  const m = moment()
   const mu = moment().utcOffset(9)
-  expect(d.valueOf()).toBe(m.valueOf())
   expect(d.valueOf()).toBe(du.valueOf())
   expect(du.valueOf()).toBe(mu.valueOf())
+  expect(d.toDate()).toEqual(du.toDate())
+  expect(du.toDate()).toEqual(mu.toDate())
 })

From 6f3a6c8e5925e143adcffc04c3177e9ea62f1f09 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:25:46 +0800
Subject: [PATCH 06/17] use constant

---
 src/plugin/setUTCOffset/index.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
index 9cd015cb0..ac5254ec3 100644
--- a/src/plugin/setUTCOffset/index.js
+++ b/src/plugin/setUTCOffset/index.js
@@ -1,3 +1,5 @@
+import { MILLISECONDS_A_MINUTE, MIN } from '../../constant'
+
 export default (option, Dayjs) => {
   const proto = Dayjs.prototype
   const oldParse = proto.parse
@@ -11,7 +13,7 @@ export default (option, Dayjs) => {
 
   proto.valueOf = function () {
     const addedOffset = !this.$utils().u(this.$offset) ? (this.$offset || 0) + localOffset : 0
-    return this.$d.valueOf() - (addedOffset * 60000)
+    return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
   }
 
   const oldUtcOffset = proto.utcOffset
@@ -28,7 +30,7 @@ export default (option, Dayjs) => {
     }
     const offset = Math.abs(input) <= 16 ? input * 60 : input
     this.$offset = offset
-    return this.add(offset + localOffset, 'minute')
+    return this.add(offset + localOffset, MIN)
   }
 
   // todo toString valueOf toDate shoud minus back to original date

From 55a7c861a67f3bc6691b48004ece24b7b0171f45 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:49:37 +0800
Subject: [PATCH 07/17] use constant

---
 src/index.js                     |  2 +-
 src/plugin/setUTCOffset/index.js |  5 +++--
 test/plugin/setUTCOffset.test.js | 14 ++++++++++++++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/index.js b/src/index.js
index 70c8ecb33..71b76b8a3 100644
--- a/src/index.js
+++ b/src/index.js
@@ -367,7 +367,7 @@ class Dayjs {
   }
 
   clone() {
-    return Utils.w(this.toDate(), this)
+    return Utils.w(this.$d, this)
   }
 
   toDate() {
diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
index ac5254ec3..8f5da2f88 100644
--- a/src/plugin/setUTCOffset/index.js
+++ b/src/plugin/setUTCOffset/index.js
@@ -29,8 +29,9 @@ export default (option, Dayjs) => {
       return oldUtcOffset.call(this)
     }
     const offset = Math.abs(input) <= 16 ? input * 60 : input
-    this.$offset = offset
-    return this.add(offset + localOffset, MIN)
+    const newD = this.add(offset + localOffset, MIN)
+    newD.$offset = offset
+    return newD
   }
 
   // todo toString valueOf toDate shoud minus back to original date
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index 5172f2cca..aeb16ed6a 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -36,3 +36,17 @@ it('valueOf, toDate should be the same as original', () => {
   expect(d.toDate()).toEqual(du.toDate())
   expect(du.toDate()).toEqual(mu.toDate())
 })
+
+it('clone', () => {
+  const du = dayjs().utcOffset(9)
+  const du2 = du.clone()
+  expect(du.valueOf()).toBe(du2.valueOf())
+  expect(du.format()).toBe(du2.format())
+})
+
+it('immutable', () => {
+  const d = dayjs()
+  const du = d.utcOffset(9)
+  expect(d.utcOffset()).not.toBe(du.utcOffset())
+  expect(d.format()).not.toBe(du.format())
+})

From e7e62450990c3b82952648762280caddd8282635 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 17:56:22 +0800
Subject: [PATCH 08/17] update tostring

---
 src/plugin/setUTCOffset/index.js | 8 +++++++-
 test/plugin/setUTCOffset.test.js | 4 +++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
index 8f5da2f88..e10cce6fc 100644
--- a/src/plugin/setUTCOffset/index.js
+++ b/src/plugin/setUTCOffset/index.js
@@ -34,5 +34,11 @@ export default (option, Dayjs) => {
     return newD
   }
 
-  // todo toString valueOf toDate shoud minus back to original date
+  proto.toISOString = function () {
+    return this.toDate().toISOString()
+  }
+
+  proto.toString = function () {
+    return this.toDate().toUTCString()
+  }
 }
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/setUTCOffset.test.js
index aeb16ed6a..2a939c7db 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/setUTCOffset.test.js
@@ -27,7 +27,7 @@ it('Set utcOffset -> Get utcOffset', () => {
   // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
 
-it('valueOf, toDate should be the same as original', () => {
+it('valueOf, toDate, toString, toISOString should be the same as original', () => {
   const d = dayjs()
   const du = dayjs().utcOffset(9)
   const mu = moment().utcOffset(9)
@@ -35,6 +35,8 @@ it('valueOf, toDate should be the same as original', () => {
   expect(du.valueOf()).toBe(mu.valueOf())
   expect(d.toDate()).toEqual(du.toDate())
   expect(du.toDate()).toEqual(mu.toDate())
+  expect(du.toISOString()).toEqual(mu.toISOString())
+  expect(d.toString()).toEqual(d.toString())
 })
 
 it('clone', () => {

From 4a22ee8b42d3290c1c64df1398016e4f331820e0 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 18:39:05 +0800
Subject: [PATCH 09/17] combine plugin

---
 src/plugin/setUTCOffset/index.js              | 44 -------------------
 src/plugin/utc/index.js                       | 37 ++++++++++++++--
 ...TCOffset.test.js => utc-utcOffset.test.js} |  4 +-
 types/plugin/setUtcOffset.d.ts                |  4 --
 4 files changed, 35 insertions(+), 54 deletions(-)
 delete mode 100644 src/plugin/setUTCOffset/index.js
 rename test/plugin/{setUTCOffset.test.js => utc-utcOffset.test.js} (95%)
 delete mode 100644 types/plugin/setUtcOffset.d.ts

diff --git a/src/plugin/setUTCOffset/index.js b/src/plugin/setUTCOffset/index.js
deleted file mode 100644
index e10cce6fc..000000000
--- a/src/plugin/setUTCOffset/index.js
+++ /dev/null
@@ -1,44 +0,0 @@
-import { MILLISECONDS_A_MINUTE, MIN } from '../../constant'
-
-export default (option, Dayjs) => {
-  const proto = Dayjs.prototype
-  const oldParse = proto.parse
-  const localOffset = (new Date()).getTimezoneOffset()
-  proto.parse = function (cfg) {
-    if (!this.$utils().u(cfg.$offset)) {
-      this.$offset = cfg.$offset
-    }
-    oldParse.call(this, cfg)
-  }
-
-  proto.valueOf = function () {
-    const addedOffset = !this.$utils().u(this.$offset) ? (this.$offset || 0) + localOffset : 0
-    return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
-  }
-
-  const oldUtcOffset = proto.utcOffset
-  proto.utcOffset = function (input) {
-    const { u } = this.$utils()
-    if (u(input)) {
-      if (this.$u) {
-        return 0
-      }
-      if (!u(this.$offset)) {
-        return this.$offset
-      }
-      return oldUtcOffset.call(this)
-    }
-    const offset = Math.abs(input) <= 16 ? input * 60 : input
-    const newD = this.add(offset + localOffset, MIN)
-    newD.$offset = offset
-    return newD
-  }
-
-  proto.toISOString = function () {
-    return this.toDate().toISOString()
-  }
-
-  proto.toString = function () {
-    return this.toDate().toUTCString()
-  }
-}
diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index d367c97be..47540bd80 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -1,4 +1,7 @@
+import { MILLISECONDS_A_MINUTE, MIN } from '../../constant'
+
 export default (option, Dayjs, dayjs) => {
+  const localOffset = (new Date()).getTimezoneOffset()
   const proto = Dayjs.prototype
   dayjs.utc = function (date, format) {
     const cfg = { date, utc: true, format }
@@ -18,6 +21,9 @@ export default (option, Dayjs, dayjs) => {
     if (cfg.utc) {
       this.$u = true
     }
+    if (!this.$utils().u(cfg.$offset)) {
+      this.$offset = cfg.$offset
+    }
     oldParse.call(this, cfg)
   }
 
@@ -39,11 +45,21 @@ export default (option, Dayjs, dayjs) => {
   }
 
   const oldUtcOffset = proto.utcOffset
-  proto.utcOffset = function () {
-    if (this.$u) {
-      return 0
+  proto.utcOffset = function (input) {
+    const { u } = this.$utils()
+    if (u(input)) {
+      if (this.$u) {
+        return 0
+      }
+      if (!u(this.$offset)) {
+        return this.$offset
+      }
+      return oldUtcOffset.call(this)
     }
-    return oldUtcOffset.call(this)
+    const offset = Math.abs(input) <= 16 ? input * 60 : input
+    const newD = this.add(offset + localOffset, MIN)
+    newD.$offset = offset
+    return newD
   }
 
   const oldFormat = proto.format
@@ -53,7 +69,20 @@ export default (option, Dayjs, dayjs) => {
     return oldFormat.call(this, str)
   }
 
+  proto.valueOf = function () {
+    const addedOffset = !this.$utils().u(this.$offset) ? (this.$offset || 0) + localOffset : 0
+    return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
+  }
+
   proto.isUTC = function () {
     return !!this.$u
   }
+
+  proto.toISOString = function () {
+    return this.toDate().toISOString()
+  }
+
+  proto.toString = function () {
+    return this.toDate().toUTCString()
+  }
 }
diff --git a/test/plugin/setUTCOffset.test.js b/test/plugin/utc-utcOffset.test.js
similarity index 95%
rename from test/plugin/setUTCOffset.test.js
rename to test/plugin/utc-utcOffset.test.js
index 2a939c7db..f6566434a 100644
--- a/test/plugin/setUTCOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -1,9 +1,9 @@
 import MockDate from 'mockdate'
 import moment from 'moment'
 import dayjs from '../../src'
-import setUTCOffset from '../../src/plugin/setUTCOffset'
+import utc from '../../src/plugin/utc'
 
-dayjs.extend(setUTCOffset)
+dayjs.extend(utc)
 
 beforeEach(() => {
   MockDate.set(new Date())
diff --git a/types/plugin/setUtcOffset.d.ts b/types/plugin/setUtcOffset.d.ts
deleted file mode 100644
index 30ec75e5d..000000000
--- a/types/plugin/setUtcOffset.d.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-import { PluginFunc } from 'dayjs'
-
-declare const plugin: PluginFunc
-export = plugin

From 814d2ae17a5900d98c20f9ee2ab31301c55d96f1 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 18:40:01 +0800
Subject: [PATCH 10/17] update test

---
 src/plugin/utc/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index 47540bd80..35e5c8c22 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -70,7 +70,7 @@ export default (option, Dayjs, dayjs) => {
   }
 
   proto.valueOf = function () {
-    const addedOffset = !this.$utils().u(this.$offset) ? (this.$offset || 0) + localOffset : 0
+    const addedOffset = !this.$utils().u(this.$offset) ? this.$offset + localOffset : 0
     return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
   }
 

From 1a8408408daa9bca88a1bf18e2511186125b0e0a Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 18:42:14 +0800
Subject: [PATCH 11/17] update test

---
 src/plugin/utc/index.js           | 3 +++
 test/plugin/utc-utcOffset.test.js | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index 35e5c8c22..15cc254f4 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -59,6 +59,9 @@ export default (option, Dayjs, dayjs) => {
     const offset = Math.abs(input) <= 16 ? input * 60 : input
     const newD = this.add(offset + localOffset, MIN)
     newD.$offset = offset
+    if (input === 0) { // UTC mode
+      newD.$u = true
+    }
     return newD
   }
 
diff --git a/test/plugin/utc-utcOffset.test.js b/test/plugin/utc-utcOffset.test.js
index f6566434a..52554ac09 100644
--- a/test/plugin/utc-utcOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -24,7 +24,7 @@ it('Set utcOffset -> Get utcOffset', () => {
 
   expect(dayjs().utcOffset(-60).format()).toBe(moment().utcOffset(-60).format())
   expect(dayjs().utcOffset(-8).format()).toBe(moment().utcOffset(-8).format())
-  // expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
+  expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
 
 it('valueOf, toDate, toString, toISOString should be the same as original', () => {

From 07644e445f2847ab8beb3751beb3e840cbbddbbe Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 18:44:33 +0800
Subject: [PATCH 12/17] update test

---
 test/plugin/utc-utcOffset.test.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/test/plugin/utc-utcOffset.test.js b/test/plugin/utc-utcOffset.test.js
index 52554ac09..c753545c6 100644
--- a/test/plugin/utc-utcOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -24,7 +24,6 @@ it('Set utcOffset -> Get utcOffset', () => {
 
   expect(dayjs().utcOffset(-60).format()).toBe(moment().utcOffset(-60).format())
   expect(dayjs().utcOffset(-8).format()).toBe(moment().utcOffset(-8).format())
-  expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
 })
 
 it('valueOf, toDate, toString, toISOString should be the same as original', () => {
@@ -52,3 +51,8 @@ it('immutable', () => {
   expect(d.utcOffset()).not.toBe(du.utcOffset())
   expect(d.format()).not.toBe(du.format())
 })
+
+it('utcOffset(0) enable utc mode', () => {
+  expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
+  expect(dayjs().utcOffset(0).isUTC()).toBeTruthy()
+})

From ad9da81c34548e1ef98d335a96f52bbf3b7bc4c2 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 19:28:15 +0800
Subject: [PATCH 13/17] update test

---
 src/plugin/utc/index.js           |  7 +++++--
 test/plugin/utc-utcOffset.test.js | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index 15cc254f4..4f781c601 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -57,10 +57,12 @@ export default (option, Dayjs, dayjs) => {
       return oldUtcOffset.call(this)
     }
     const offset = Math.abs(input) <= 16 ? input * 60 : input
-    const newD = this.add(offset + localOffset, MIN)
+    const newD = this.add(offset + (this.$u ? 0 : localOffset), MIN)
     newD.$offset = offset
     if (input === 0) { // UTC mode
       newD.$u = true
+    } else {
+      newD.$u = false
     }
     return newD
   }
@@ -73,7 +75,8 @@ export default (option, Dayjs, dayjs) => {
   }
 
   proto.valueOf = function () {
-    const addedOffset = !this.$utils().u(this.$offset) ? this.$offset + localOffset : 0
+    const addedOffset = !this.$utils().u(this.$offset)
+      ? this.$offset + (this.$u ? 0 : localOffset) : 0
     return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
   }
 
diff --git a/test/plugin/utc-utcOffset.test.js b/test/plugin/utc-utcOffset.test.js
index c753545c6..0419d438d 100644
--- a/test/plugin/utc-utcOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -56,3 +56,18 @@ it('utcOffset(0) enable utc mode', () => {
   expect(dayjs().utcOffset(0).format()).toBe(moment().utcOffset(0).format())
   expect(dayjs().utcOffset(0).isUTC()).toBeTruthy()
 })
+
+test('UTC mode', () => {
+  const d = dayjs.utc('2000-01-01T06:00:00Z')
+  expect(d.isUTC()).toBeTruthy()
+  expect(d.utcOffset(0).isUTC()).toBeTruthy()
+  expect(d.utcOffset(1).isUTC()).toBeFalsy()
+})
+
+test('change hours when changing the utc offset in UTC mode', () => {
+  const d = dayjs.utc('2000-01-01T06:00:00Z')
+  expect(d.hour()).toBe(6)
+  expect(d.utcOffset(0).hour()).toBe(6)
+  expect(d.utcOffset(-60).hour()).toBe(5)
+  expect(d.utcOffset(60).hour()).toBe(7)
+})

From 0b51b50fd4dbdf97c8e8aac469fe03413cc570bd Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 19:29:48 +0800
Subject: [PATCH 14/17] update test

---
 src/plugin/utc/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index 4f781c601..43dc86477 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -76,7 +76,7 @@ export default (option, Dayjs, dayjs) => {
 
   proto.valueOf = function () {
     const addedOffset = !this.$utils().u(this.$offset)
-      ? this.$offset + (this.$u ? 0 : localOffset) : 0
+      ? this.$offset + localOffset : 0
     return this.$d.valueOf() - (addedOffset * MILLISECONDS_A_MINUTE)
   }
 

From 294a5df9a5dbbd85850c88e709f6f2b296afee07 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 19:31:22 +0800
Subject: [PATCH 15/17] update test

---
 test/plugin/utc-utcOffset.test.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/test/plugin/utc-utcOffset.test.js b/test/plugin/utc-utcOffset.test.js
index 0419d438d..3f82b9702 100644
--- a/test/plugin/utc-utcOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -65,9 +65,12 @@ test('UTC mode', () => {
 })
 
 test('change hours when changing the utc offset in UTC mode', () => {
-  const d = dayjs.utc('2000-01-01T06:00:00Z')
+  const d = dayjs.utc('2000-01-01T06:31:00Z')
   expect(d.hour()).toBe(6)
   expect(d.utcOffset(0).hour()).toBe(6)
   expect(d.utcOffset(-60).hour()).toBe(5)
   expect(d.utcOffset(60).hour()).toBe(7)
+  expect(d.utcOffset(-30).format('HH:mm')).toBe('06:01')
+  expect(d.utcOffset(30).format('HH:mm')).toBe('07:01')
+  expect(d.utcOffset(-1380).format('HH:mm')).toBe('07:31')
 })

From 95bde733d3d7b2e0a7185a185ac4738783fd77d4 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Wed, 21 Aug 2019 19:35:01 +0800
Subject: [PATCH 16/17] update test

---
 test/plugin/utc-utcOffset.test.js | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/test/plugin/utc-utcOffset.test.js b/test/plugin/utc-utcOffset.test.js
index 3f82b9702..bd652be7a 100644
--- a/test/plugin/utc-utcOffset.test.js
+++ b/test/plugin/utc-utcOffset.test.js
@@ -40,9 +40,10 @@ it('valueOf, toDate, toString, toISOString should be the same as original', () =
 
 it('clone', () => {
   const du = dayjs().utcOffset(9)
-  const du2 = du.clone()
-  expect(du.valueOf()).toBe(du2.valueOf())
-  expect(du.format()).toBe(du2.format())
+  const duClone = du.clone()
+  expect(du.valueOf()).toBe(duClone.valueOf())
+  expect(du.format()).toBe(duClone.format())
+  expect(du.utcOffset()).toBe(duClone.utcOffset())
 })
 
 it('immutable', () => {

From 56fb33155060a8c119c63750016e60dcfcee2634 Mon Sep 17 00:00:00 2001
From: iamkun <kunhello@outlook.com>
Date: Tue, 27 Aug 2019 15:29:28 +0800
Subject: [PATCH 17/17] update type

---
 src/plugin/utc/index.js | 6 +-----
 types/plugin/utc.d.ts   | 2 ++
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
index 43dc86477..40c6a4959 100644
--- a/src/plugin/utc/index.js
+++ b/src/plugin/utc/index.js
@@ -59,11 +59,7 @@ export default (option, Dayjs, dayjs) => {
     const offset = Math.abs(input) <= 16 ? input * 60 : input
     const newD = this.add(offset + (this.$u ? 0 : localOffset), MIN)
     newD.$offset = offset
-    if (input === 0) { // UTC mode
-      newD.$u = true
-    } else {
-      newD.$u = false
-    }
+    newD.$u = input === 0 // UTC mode
     return newD
   }
 
diff --git a/types/plugin/utc.d.ts b/types/plugin/utc.d.ts
index 2f14efb22..d25e2e847 100644
--- a/types/plugin/utc.d.ts
+++ b/types/plugin/utc.d.ts
@@ -11,6 +11,8 @@ declare module 'dayjs' {
     local(): Dayjs
 
     isUTC(): boolean
+
+    utcOffset(offset: number): Dayjs
   }
 
   export function utc(config?: ConfigType, format?: string): Dayjs