diff --git a/docs/en/API-reference.md b/docs/en/API-reference.md
index 54ee2a3b6..53102fec1 100644
--- a/docs/en/API-reference.md
+++ b/docs/en/API-reference.md
@@ -39,10 +39,8 @@ The `Dayjs` object is immutable, that is, all API operations that change the `Da
     - [UTC offset (minutes) `.utcOffset()`](#utc-offset-minutes-utcoffset)
     - [Days in the Month `.daysInMonth()`](#days-in-the-month-daysinmonth)
     - [As Javascript Date `.toDate()`](#as-javascript-date-todate)
-    - [As Array `.toArray()`](#as-array-toarray)
     - [As JSON `.toJSON()`](#as-json-tojson)
     - [As ISO 8601 String `.toISOString()`](#as-iso-8601-string-toisostring)
-    - [As Object `.toObject()`](#as-object-toobject)
     - [As String `.toString()`](#as-string-tostring)
   - [Query](#query)
     - [Is Before `.isBefore(compared: Dayjs, unit?: string)`](#is-before-isbeforecompared-dayjs-unit-string)
@@ -58,6 +56,8 @@ The `Dayjs` object is immutable, that is, all API operations that change the `Da
     - [IsSameOrBefore](#issameorbefore)
     - [IsBetween](#isbetween)
     - [QuarterOfYear](#quarterofyear)
+    - [ToArray](#toarray)
+    - [ToObject](#toobject)
 
 ## Parsing
 
@@ -125,66 +125,74 @@ dayjs().isValid()
 
 ### Year `.year()`
 
-Returns a `number` representing the `Dayjs`'s year.
+Gets or sets the year.
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 ### Month `.month()`
 
-Returns a `number` representing the `Dayjs`'s month. Starts at 0
+Gets or sets the month. Starts at 0
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 ### Day of the Month `.date()`
 
-Returns a `number` representing the `Dayjs`'s day of the month. Starts at 1
+Gets or sets the day of the month. Starts at 1
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 ### Day of the Week `.day()`
 
-Returns a `number` representing the `Dayjs`'s day of the week. Starts on Sunday with 0
+Gets or sets the day of the week. Starts on Sunday with 0
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 ### Hour `.hour()`
 
-Returns a `number` representing the `Dayjs`'s hour.
+Gets or sets the hour.
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 ### Minute `.minute()`
 
-Returns a `number` representing the `Dayjs`'s minute.
+Gets or sets the minute.
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 ### Second `.second()`
 
-Returns a `number` representing the `Dayjs`'s second.
+Gets or sets the second.
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 ### Millisecond `.millisecond()`
 
-Returns a `number` representing the `Dayjs`'s millisecond.
+Gets or sets the millisecond.
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 ### Set `.set(unit: string, value: number)`
@@ -354,14 +362,6 @@ Returns a copy of the native `Date` object parsed from the `Dayjs` object.
 dayjs('2019-01-25').toDate()
 ```
 
-### As Array `.toArray()`
-
-Returns an `array` that mirrors the parameters from new Date().
-
-```js
-dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
-```
-
 ### As JSON `.toJSON()`
 
 Returns the `Dayjs` formatted in an ISO8601 `string`.
@@ -378,21 +378,6 @@ Returns the `Dayjs` formatted in an ISO8601 `string`.
 dayjs('2019-01-25').toISOString() // '2019-01-25T02:00:00.000Z'
 ```
 
-### As Object `.toObject()`
-
-Returns an `object` with the date's properties.
-
-```js
-dayjs('2019-01-25').toObject()
-/* { years: 2019,
-     months: 0,
-     date: 25,
-     hours: 0,
-     minutes: 0,
-     seconds: 0,
-     milliseconds: 0 } */
-```
-
 ### As String `.toString()`
 
 Returns a `string` representation of the date.
@@ -492,3 +477,15 @@ plugin [`IsBetween`](./Plugin.md#isbetween)
 `.quarter` to get quarter of the year
 
 plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### ToArray
+
+`.toArray` to return an `array` that mirrors the parameters
+
+plugin [`ToArray`](./Plugin.md#toarray)
+
+### ToObject
+
+`.toObject` to return an `object` with the date's properties.
+
+plugin [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/en/Plugin.md b/docs/en/Plugin.md
index 56823fb09..bddd23bdf 100644
--- a/docs/en/Plugin.md
+++ b/docs/en/Plugin.md
@@ -339,6 +339,38 @@ dayjs('2018 Enero 15', 'YYYY MMMM DD', 'es')
 | `ZZ`   | -0500            | Compact offset from UTC, 2-digits |
 | `A`    | AM PM            | Post or ante meridiem, upper-case |
 | `a`    | am pm            | Post or ante meridiem, lower-case |
+| `Do`   | 1st... 31st      | Day of Month with ordinal         |
+
+### ToArray
+
+- ToArray add `.toArray()` API to return an `array` that mirrors the parameters
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject add `.toObject()` API to return an `object` with the date's properties.
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## Customize
 
diff --git a/docs/es-es/API-reference.md b/docs/es-es/API-reference.md
index b165afcc3..d26c925a4 100644
--- a/docs/es-es/API-reference.md
+++ b/docs/es-es/API-reference.md
@@ -39,10 +39,8 @@ El objeto `Dayjs` es inmutable, por lo que toda operación de la API que altere
     - [UTC offset (minutos) `.utcOffset()`](#utc-offset-minutos-utcoffset)
     - [Días en el mes `.daysInMonth()`](#días-en-el-mes-daysinmonth)
     - [Como objeto `Date` `.toDate()`](#como-objeto-date-todate)
-    - [Como array `.toArray()`](#como-array-toarray)
     - [Como JSON `.toJSON()`](#como-json-tojson)
     - [Como cadena ISO 8601 `.toISOString()`](#como-cadena-iso-8601-toisostring)
-    - [Como objeto `.toObject()`](#como-objecto-toobject)
     - [Como cadena `.toString()`](#como-cadena-tostring)
   - [Consulta](#consulta)
     - [Anterior a `.isBefore(compared: Dayjs, unit?: string)`](#anterior-a-isbeforecompared-dayjs-unit-string)
@@ -58,6 +56,8 @@ El objeto `Dayjs` es inmutable, por lo que toda operación de la API que altere
     - [IsSameOrBefore](#issameorbefore)
     - [IsBetween](#isbetween)
     - [QuarterOfYear](#quarterofyear)
+    - [ToArray](#toarray)
+    - [ToObject](#toobject)
 
 ## Análisis
 
@@ -125,66 +125,74 @@ dayjs().isValid()
 
 ### Año `.year()`
 
-Devuelve un dato de tipo `number`, que representa el año del objeto `Dayjs`.
+Gets or sets the year.
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 ### Mes `.month()`
 
-Devuelve un dato de tipo `number`, que representa el mes del objeto `Dayjs`. Se cuenta desde 0, que se corresponde con enero.
+Gets or sets the month. Starts at 0
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 ### Día del mes `.date()`
 
-Devuelve un dato de tipo `number`, que indica el día del mes del objeto `Dayjs`. Empieza por el día 1.
+Gets or sets the day of the month. Starts at 1
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 ### Día de la semana `.day()`
 
-Devuelve un dato de tipo `number`, que indica el día de la semana del objeto `Dayjs`. Se cuenta desde 0, que se corresponde con el domingo.
+Gets or sets the day of the week. Starts on Sunday with 0
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 ### Hora `.hour()`
 
-Devuelve un dato de tipo `number`, que indica la hora del objeto `Dayjs`.
+Gets or sets the hour.
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 ### Minuto `.minute()`
 
-Devuelve un dato de tipo `number`, que indica los minutos del objeto `Dayjs`.
+Gets or sets the minute.
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 ### Segundo `.second()`
 
-Devuelve un dato de tipo `number`, que indica los segundos del objeto `Dayjs`.
+Gets or sets the second.
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 ### Milisegundo `.millisecond()`
 
-Devuelve un dato de tipo `number`, que indica los milisegundos del objeto `Dayjs`.
+Gets or sets the millisecond.
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 ### Set `.set(unit: string, value: number)`
@@ -354,14 +362,6 @@ Devuelve un objeto `Date` nativo, obtenido a partir del objeto `Dayjs`.
 dayjs('2019-01-25').toDate()
 ```
 
-### Como array `.toArray()`
-
-Devuelve un array que reproduce los parámetros de `new Date()`.
-
-```js
-dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
-```
-
 ### Como JSON `.toJSON()`
 
 Devuelve un objeto `Dayjs` formateado como una cadena ISO8601.
@@ -378,21 +378,6 @@ Devuelve un objeto `Dayjs` formateado como una cadena ISO8601.
 dayjs('2019-01-25').toISOString() // '2019-01-25T02:00:00.000Z'
 ```
 
-### Como objecto `.toObject()`
-
-Devuelve un dato de tipo `object`, con las propiedades de la fecha.
-
-```js
-dayjs('2019-01-25').toObject()
-/* { years: 2019,
-     months: 0,
-     date: 25,
-     hours: 0,
-     minutes: 0,
-     seconds: 0,
-     milliseconds: 0 } */
-```
-
 ### Como cadena `.toString()`
 
 Devuelve un dato de tipo `string`, que representa la fecha.
@@ -492,3 +477,15 @@ complemento [`IsBetween`](./Plugin.md#isbetween)
 `.quarter` to get quarter of the year
 
 plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### ToArray
+
+`.toArray` to return an `array` that mirrors the parameters
+
+plugin [`ToArray`](./Plugin.md#toarray)
+
+### ToObject
+
+`.toObject` to return an `object` with the date's properties.
+
+plugin [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/es-es/Plugin.md b/docs/es-es/Plugin.md
index 08256ab4a..9d30c29f1 100644
--- a/docs/es-es/Plugin.md
+++ b/docs/es-es/Plugin.md
@@ -339,6 +339,38 @@ dayjs('2018 Enero 15', 'YYYY MMMM DD', 'es')
 | `ZZ`   | -0500            | Compact offset from UTC, 2-digits |
 | `A`    | AM PM            | Post or ante meridiem, upper-case |
 | `a`    | am pm            | Post or ante meridiem, lower-case |
+| `Do`   | 1st... 31st      | Día del mes con ordinal           |
+
+### ToArray
+
+- ToArray add `.toArray()` API to return an `array` that mirrors the parameters
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject add `.toObject()` API to return an `object` with the date's properties.
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## Personalización
 
diff --git a/docs/ja/API-reference.md b/docs/ja/API-reference.md
index 57357a0da..57daefcbe 100644
--- a/docs/ja/API-reference.md
+++ b/docs/ja/API-reference.md
@@ -36,10 +36,8 @@ Day.js は組み込みの `Date.prototype` を変更する代わりに `Dayjs` 
   - [UTC offset (minutes)](#utc-offset-minutes-utcoffset)
   - [Days in Month](#days-in-month)
   - [As Javascript Date](#as-javascript-date)
-  - [As Array](#as-array)
   - [As JSON](#as-json)
   - [As ISO 8601 String](#as-iso-8601-string)
-  - [As Object](#as-object)
   - [As String](#as-string)
 - [Query](#query)
   - [Is Before](#is-before)
@@ -55,6 +53,8 @@ Day.js は組み込みの `Date.prototype` を変更する代わりに `Dayjs` 
   - [IsSameOrBefore](#issameorbefore)
   - [IsBetween](#isbetween)
   - [QuarterOfYear](#quarterofyear)
+  - [ToArray](#toarray)
+  - [ToObject](#toobject)
 
 ---
 
@@ -138,82 +138,74 @@ dayjs().isValid()
 
 #### Year
 
-- Number を返します
-
-年を取得します。
+Gets or sets the year.
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 #### Month
 
-- Number を返します
-
-月を取得します。
+Gets or sets the month. Starts at 0
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 #### Date of Month
 
-- Number を返します
-
-日を取得します。
+Gets or sets the day of the month. Starts at 1
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 #### Day of Week
 
-- Number を返します
-
-曜日を取得します。
+Gets or sets the day of the week. Starts on Sunday with 0
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 #### Hour
 
-- Number を返します
-
-時間を取得します。
+Gets or sets the hour.
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 #### Minute
 
-- Number を返します
-
-分を取得します。
+Gets or sets the minute.
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 #### Second
 
-- Number を返します
-
-秒を取得します。
+Gets or sets the second.
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 #### Millisecond
 
-- Number を返します
-
-ミリ秒を取得します。
+Gets or sets the millisecond.
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 #### Set
@@ -408,16 +400,6 @@ dayjs().daysInMonth()
 dayjs().toDate()
 ```
 
-#### As Array
-
-- Array を返します
-
-Date コンストラクタパラメータに対応する値の配列を返します。
-
-```js
-dayjs().toArray() //[2018, 8, 18, 00, 00, 00, 000];
-```
-
 #### As JSON
 
 - JSON String を返します
@@ -438,16 +420,6 @@ ISO8601 形式の文字列にフォーマットします。
 dayjs().toISOString()
 ```
 
-#### As Object
-
-- Object を返します
-
-年、月、...（中略）...、ミリ秒のオブジェクトを返します。
-
-```js
-dayjs().toObject() // { years:2018, months:8, date:18, hours:0, minutes:0, seconds:0, milliseconds:0}
-```
-
 #### As String
 
 - String を返します
@@ -561,3 +533,15 @@ plugin [`IsBetween`](./Plugin.md#isbetween)
 `.quarter` to get quarter of the year
 
 plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### ToArray
+
+`.toArray` to return an `array` that mirrors the parameters
+
+plugin [`ToArray`](./Plugin.md#toarray)
+
+### ToObject
+
+`.toObject` to return an `object` with the date's properties.
+
+plugin [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/ja/Plugin.md b/docs/ja/Plugin.md
index 22a3da15e..db28bcc58 100644
--- a/docs/ja/Plugin.md
+++ b/docs/ja/Plugin.md
@@ -348,6 +348,38 @@ dayjs('2018 5月 15', 'YYYY MMMM DD', 'ja')
 | `ZZ`   | -0500            | Compact offset from UTC, 2-digits |
 | `A`    | AM PM            | Post or ante meridiem, upper-case |
 | `a`    | am pm            | Post or ante meridiem, lower-case |
+| `Do`   | 1st... 31st      | 序数付きの日                      |
+
+### ToArray
+
+- ToArray add `.toArray()` API to return an `array` that mirrors the parameters
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject add `.toObject()` API to return an `object` with the date's properties.
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## カスタマイズ
 
diff --git a/docs/ko/API-reference.md b/docs/ko/API-reference.md
index 62bcf83d0..01fa80488 100644
--- a/docs/ko/API-reference.md
+++ b/docs/ko/API-reference.md
@@ -38,10 +38,8 @@ Day.js는 네이티브 `Date.prototype`을 수정하는 대신 `Dayjs` 오브젝
     - [UTC offset (minutes) `.utcOffset()`](#utc-offset-minutes-utcoffset)
     - [Days in the Month `.daysInMonth()`](#days-in-the-month-daysinmonth)
     - [As Javascript Date `.toDate()`](#as-javascript-date-todate)
-    - [As Array `.toArray()`](#as-array-toarray)
     - [As JSON `.toJSON()`](#as-json-tojson)
     - [As ISO 8601 String `.toISOString()`](#as-iso-8601-string-toisostring)
-    - [As Object `.toObject()`](#as-object-toobject)
     - [As String `.toString()`](#as-string-tostring)
   - [Query](#query)
     - [Is Before `.isBefore(compared: Dayjs, unit?: string)`](#is-before-isbeforecompared--dayjs-unit-string)
@@ -57,6 +55,8 @@ Day.js는 네이티브 `Date.prototype`을 수정하는 대신 `Dayjs` 오브젝
     - [IsSameOrBefore](#issameorbefore)
     - [IsBetween](#isbetween)
     - [QuarterOfYear](#quarterofyear)
+    - [ToArray](#toarray)
+    - [ToObject](#toobject)
 
 ## Parsing
 
@@ -124,66 +124,74 @@ dayjs().isValid()
 
 ### Year `.year()`
 
-`Dayjs`에서 연도 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the year.
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 ### Month `.month()`
 
-`Dayjs`에서 달을 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the month. Starts at 0
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 ### Day of the Month `.date()`
 
-`Dayjs`에서 날짜를 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the day of the month. Starts at 1
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 ### Day of the Week `.day()`
 
-`Dayjs`에서 요일을 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the day of the week. Starts on Sunday with 0
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 ### Hour `.hour()`
 
-`Dayjs`에서 시를 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the hour.
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 ### Minute `.minute()`
 
-`Dayjs`에서 분을 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the minute.
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 ### Second `.second()`
 
-`Dayjs`에서 초를 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the second.
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 ### Millisecond `.millisecond()`
 
-`Dayjs`에서 밀리 초를 가져옵니다. 반환 타입은 `number` 입니다.
+Gets or sets the millisecond.
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 ### Set `.set(unit: string, value: number)`
@@ -353,14 +361,6 @@ dayjs('2019-01-25').daysInMonth() // 31
 dayjs('2019-01-25').toDate()
 ```
 
-### As Array `.toArray()`
-
-새로운 `Date()`로부터 매개변수로 입력한 날짜를 가져옵니다. 반환 타입은 `array` 입니다.
-
-```js
-dayjs('2019-01-25').toArray() // [ 2019, 01, 25, 0, 0, 0, 0 ]
-```
-
 ### As JSON `.toJSON()`
 
 ISO8601에 대한 형식으로 `Dayjs`를 출력합니다. 반환 타입은 `string` 입니다.
@@ -377,21 +377,6 @@ ISO8601에 대한 형식으로 `Dayjs`를 출력합니다. 반환 타입은 `str
 dayjs('2019-01-25').toISOString() // '2019-01-25T02:00:00.000Z'
 ```
 
-### As Object `.toObject()`
-
-날짜 속성을 가진 `object` 타입 값으로 반환합니다.
-
-```js
-dayjs('2019-01-25').toObject()
-/* { years: 2019,
-     months: 0,
-     date: 25,
-     hours: 0,
-     minutes: 0,
-     seconds: 0,
-     milliseconds: 0 } */
-```
-
 ### As String `.toString()`
 
 날짜를 `string` 타입 값으로 반환합니다.
@@ -491,3 +476,15 @@ plugin [`IsBetween`](./Plugin.md#isbetween)
 `.quarter` to get quarter of the year
 
 plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### ToArray
+
+`.toArray` to return an `array` that mirrors the parameters
+
+plugin [`ToArray`](./Plugin.md#toarray)
+
+### ToObject
+
+`.toObject` to return an `object` with the date's properties.
+
+plugin [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/ko/Plugin.md b/docs/ko/Plugin.md
index 8463ae241..af6f11016 100644
--- a/docs/ko/Plugin.md
+++ b/docs/ko/Plugin.md
@@ -340,6 +340,38 @@ dayjs('2018 5월 15', 'YYYY MMMM DD', 'ko')
 | `ZZ`   | -0500            | Compact offset from UTC, 2-digits |
 | `A`    | AM PM            | Post or ante meridiem, upper-case |
 | `a`    | am pm            | Post or ante meridiem, lower-case |
+| `Do`   | 1st... 31st      | 서수형식의 일자 명                |
+
+### ToArray
+
+- ToArray add `.toArray()` API to return an `array` that mirrors the parameters
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject add `.toObject()` API to return an `object` with the date's properties.
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## Customize
 
diff --git a/docs/pt-br/API-reference.md b/docs/pt-br/API-reference.md
index baa9857d7..2213127c4 100644
--- a/docs/pt-br/API-reference.md
+++ b/docs/pt-br/API-reference.md
@@ -39,10 +39,8 @@ O objeto `Dayjs` é imutável, ou seja, todas as operações da API que alteram
     - [UTC offset (minutes) `.utcOffset()`](#utc-offset-minutes-utcoffset)
     - [Dias no Mês `.daysInMonth()`](#dias-no-mês-daysinmonth)
     - [Como objeto `Date` do Javascript `.toDate()`](#como-objeto-date-do-javascript-todate)
-    - [Como Array `.toArray()`](#como-array-toarray)
     - [Como JSON `.toJSON()`](#como-json-tojson)
     - [Como uma string ISO 8601 `.toISOString()`](#como-uma-string-iso-8601-toisostring)
-    - [Como Objeto `.toObject()`](#como-objeto-toobject)
     - [Como String `.toString()`](#como-string-tostring)
   - [Consulta](#consulta)
     - [Antes `.isBefore(compared: Dayjs, unit?: string)`](#antes-isbeforecompared-dayjs-unit-string)
@@ -58,6 +56,8 @@ O objeto `Dayjs` é imutável, ou seja, todas as operações da API que alteram
     - [IsSameOrBefore](#issameorbefore)
     - [IsBetween](#isbetween)
     - [QuarterOfYear](#quarterofyear)
+    - [ToArray](#toarray)
+    - [ToObject](#toobject)
 
 ## Conversões
 
@@ -123,66 +123,74 @@ dayjs().isValid()
 
 ### Ano `.year()`
 
-Retorna um `number` representando o ano do objeto `Dayjs`.
+Gets or sets the year.
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 ### Mês `.month()`
 
-Retorna um `number` representando o mês do objeto `Dayjs`.
+Gets or sets the month. Starts at 0
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 ### Dia do Mês `.date()`
 
-Retorna um `number` representando o dia do mês do objeto `Dayjs`.
+Gets or sets the day of the month. Starts at 1
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 ### Dia da Semana `.day()`
 
-Retorna um `number` representando o dia da semana do objeto `Dayjs`.
+Gets or sets the day of the week. Starts on Sunday with 0
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 ### Hora `.hour()`
 
-Retorna um `number` representando a hora do objeto `Dayjs`.
+Gets or sets the hour.
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 ### Minuto `.minute()`
 
-Retorna um `number` representando os minutos do objeto `Dayjs`.
+Gets or sets the minute.
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 ### Segundo `.second()`
 
-Retorna um `number` representando os segundos do objeto `Dayjs`.
+Gets or sets the second.
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 ### Milissegundo `.millisecond()`
 
-Retorna um `number` representando os milissegundos do objeto `Dayjs`.
+Gets or sets the millisecond.
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 ### Set `.set(unit: string, value: number)`
@@ -352,14 +360,6 @@ Retorna uma cópia do objeto nativo `Date` convertido de um objeto `Dayjs`.
 dayjs('2019-01-25').toDate()
 ```
 
-### Como Array `.toArray()`
-
-Retorna um `array` que espelha os parâmetros de um new Date().
-
-```js
-dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
-```
-
 ### Como JSON `.toJSON()`
 
 Retorna o objeto `Dayjs` formatado em uma `string` ISO8601.
@@ -376,21 +376,6 @@ Retorna o objeto `Dayjs` formatado em uma `string` ISO8601.
 dayjs('2019-01-25').toISOString() // '2019-01-25T02:00:00.000Z'
 ```
 
-### Como Objeto `.toObject()`
-
-Retorna um `object` com as propriedades da data.
-
-```js
-dayjs('2019-01-25').toObject()
-/* { years: 2019,
-     months: 0,
-     date: 25,
-     hours: 0,
-     minutes: 0,
-     seconds: 0,
-     milliseconds: 0 } */
-```
-
 ### Como String `.toString()`
 
 Retorna uma representação em `string` da data.
@@ -490,3 +475,15 @@ plugin [`IsBetween`](./Plugin.md#isbetween)
 `.quarter` to get quarter of the year
 
 plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### ToArray
+
+`.toArray` to return an `array` that mirrors the parameters
+
+plugin [`ToArray`](./Plugin.md#toarray)
+
+### ToObject
+
+`.toObject` to return an `object` with the date's properties.
+
+plugin [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/pt-br/Plugin.md b/docs/pt-br/Plugin.md
index 687cea35f..2fa6af1b5 100644
--- a/docs/pt-br/Plugin.md
+++ b/docs/pt-br/Plugin.md
@@ -339,6 +339,38 @@ dayjs('2018 Fevereiro 15', 'YYYY MMMM DD', 'pt_br')
 | `ZZ`   | -0500            | Compact offset from UTC, 2-digits |
 | `A`    | AM PM            | Post or ante meridiem, upper-case |
 | `a`    | am pm            | Post or ante meridiem, lower-case |
+| `Do`   | 1st... 31st      | Dia do mês com ordinal            |
+
+### ToArray
+
+- ToArray add `.toArray()` API to return an `array` that mirrors the parameters
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject add `.toObject()` API to return an `object` with the date's properties.
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## Customizar
 
diff --git a/docs/zh-cn/API-reference.md b/docs/zh-cn/API-reference.md
index 468fa65ee..aa96f2891 100644
--- a/docs/zh-cn/API-reference.md
+++ b/docs/zh-cn/API-reference.md
@@ -36,10 +36,8 @@
   - [UTC 偏移量 (分)](#utc-偏移量-分)
   - [天数 (月)](#天数-月)
   - [Date 对象](#date-对象-1)
-  - [数组](#数组)
   - [JSON](#as-json)
   - [ISO 8601 字符串](#iso-8601-字符串)
-  - [对象](#对象)
   - [字符串](#字符串)
 - [查询](#查询)
   - [是否之前](#是否之前)
@@ -55,6 +53,8 @@
   - [是否相同或之前](#是否相同或之前)
   - [是否之间](#是否之间)
   - [年中第几季度](#年中第几季度)
+  - [转成数组](#转成数组)
+  - [转成对象](#转成对象)
 
 ---
 
@@ -140,82 +140,74 @@ dayjs().isValid()
 
 #### 年
 
-- return Number
-
-获取年份。
+获取或设置年份。
 
 ```js
 dayjs().year()
+dayjs().year(2000)
 ```
 
 #### 月
 
-- return Number
-
-获取月份。
+获取或设置月份。从 0 开始
 
 ```js
 dayjs().month()
+dayjs().month(0)
 ```
 
 #### 日
 
-- return Number
-
-获取日期。
+获取或设置日期。从 1 开始
 
 ```js
 dayjs().date()
+dayjs().date(1)
 ```
 
 #### 星期
 
-- return Number
-
-获取星期。
+获取或设置星期。从星期天 0 开始
 
 ```js
 dayjs().day()
+dayjs().day(0)
 ```
 
 #### 时
 
-- return Number
-
-获取小时。
+获取或设置小时。
 
 ```js
 dayjs().hour()
+dayjs().hour(12)
 ```
 
 #### 分
 
-- return Number
-
-获取分钟。
+获取或设置分钟。
 
 ```js
 dayjs().minute()
+dayjs().minute(59)
 ```
 
 #### 秒
 
-- return Number
-
-获取秒。
+获取或设置秒。
 
 ```js
 dayjs().second()
+dayjs().second(1)
 ```
 
 #### 毫秒
 
-- return Number
-
-获取毫秒。
+获取或设置毫秒。
 
 ```js
 dayjs().millisecond()
+dayjs().millisecond(1)
 ```
 
 #### 设置
@@ -406,16 +398,6 @@ dayjs().daysInMonth()
 dayjs().toDate()
 ```
 
-#### 数组
-
-- return Array
-
-返回包含时间数值的数组。
-
-```js
-dayjs().toArray() //[2018, 8, 18, 00, 00, 00, 000];
-```
-
 #### As JSON
 
 - return JSON String
@@ -436,16 +418,6 @@ dayjs().toJSON() //"2018-08-08T00:00:00.000Z"
 dayjs().toISOString()
 ```
 
-#### 对象
-
-- return Object
-
-返回包含时间数值的对象。
-
-```js
-dayjs().toObject() // { years:2018, months:8, date:18, hours:0, minutes:0, seconds:0, milliseconds:0}
-```
-
 #### 字符串
 
 - return String
@@ -537,22 +509,34 @@ dayjs() instanceof dayjs // true
 
 `.isSameOrAfter` 返回一个时间和一个时间相同或在一个时间之后
 
-plugin [`IsSameOrAfter`](./Plugin.md#issameorafter)
+插件 [`IsSameOrAfter`](./Plugin.md#issameorafter)
 
 ### 是否相同或之前
 
 `.isSameOrBefore` 返回一个时间是否和一个时间相同或在一个时间之前
 
-plugin [`IsSameOrBefore`](./Plugin.md#issameorbefore)
+插件 [`IsSameOrBefore`](./Plugin.md#issameorbefore)
 
 ### 是否之间
 
 `.isBetween` 返回一个时间是否介于两个时间之间
 
-plugin [`IsBetween`](./Plugin.md#isbetween)
+插件 [`IsBetween`](./Plugin.md#isbetween)
 
 ### 年中第几季度
 
 `.quarter` 返回年中第几季度
 
-plugin [`QuarterOfYear`](./Plugin.md#quarterofyear)
+插件 [`QuarterOfYear`](./Plugin.md#quarterofyear)
+
+### 转成数组
+
+`.toArray` 返回包含时间数值的数组。
+
+插件 [`ToArray`](./Plugin.md#toarray)
+
+### 转成对象
+
+`.toObject` 返回包含时间数值的对象
+
+插件 [`ToObject`](./Plugin.md#toobject)
diff --git a/docs/zh-cn/Plugin.md b/docs/zh-cn/Plugin.md
index 6aa714614..c5c0ae2b3 100644
--- a/docs/zh-cn/Plugin.md
+++ b/docs/zh-cn/Plugin.md
@@ -338,6 +338,38 @@ dayjs('2018 五月 15', 'YYYY MMMM DD', 'zh_cn')
 | `ZZ`   | +0500            | UTC 的偏移量，数字前面加上 0 |
 | `A`    | AM PM            |                              |
 | `a`    | am pm            |                              |
+| `Do`   | 1st... 31st      | 带序号的月份                 |
+
+### ToArray
+
+- ToArray 增加了 `.toArray()` API 来返回包含时间数值的数组。
+
+```javascript
+import toArray from 'dayjs/plugin/toArray'
+
+dayjs.extend(toArray)
+
+dayjs('2019-01-25').toArray() // [ 2019, 0, 25, 0, 0, 0, 0 ]
+```
+
+### ToObject
+
+- ToObject 增加了 `.toObject()` API 来返回包含时间数值的对象。
+
+```javascript
+import toObject from 'dayjs/plugin/toObject'
+
+dayjs.extend(toObject)
+
+dayjs('2019-01-25').toObject()
+/* { years: 2019,
+     months: 0,
+     date: 25,
+     hours: 0,
+     minutes: 0,
+     seconds: 0,
+     milliseconds: 0 } */
+```
 
 ## 自定义
 
diff --git a/src/index.js b/src/index.js
index 4f96f9c91..ffdbe9671 100644
--- a/src/index.js
+++ b/src/index.js
@@ -109,36 +109,41 @@ class Dayjs {
     return this.endOf(units) < dayjs(that)
   }
 
-  year() {
-    return this.$y
+  $g(input, get, set) {
+    if (Utils.u(input)) return this[get]
+    return this.set(set, input)
   }
 
-  month() {
-    return this.$M
+  year(input) {
+    return this.$g(input, '$y', C.Y)
   }
 
-  day() {
-    return this.$W
+  month(input) {
+    return this.$g(input, '$M', C.M)
   }
 
-  date() {
-    return this.$D
+  day(input) {
+    return this.$g(input, '$W', C.D)
   }
 
-  hour() {
-    return this.$H
+  date(input) {
+    return this.$g(input, '$D', C.DATE)
   }
 
-  minute() {
-    return this.$m
+  hour(input) {
+    return this.$g(input, '$H', C.H)
   }
 
-  second() {
-    return this.$s
+  minute(input) {
+    return this.$g(input, '$m', C.MIN)
   }
 
-  millisecond() {
-    return this.$ms
+  second(input) {
+    return this.$g(input, '$s', C.S)
+  }
+
+  millisecond(input) {
+    return this.$g(input, '$ms', C.MS)
   }
 
   unix() {
@@ -227,7 +232,8 @@ class Dayjs {
     number = Number(number) // eslint-disable-line no-param-reassign
     const unit = Utils.p(units)
     const instanceFactory = (u, n) => {
-      const date = this.set(C.DATE, 1).set(u, n + number)
+      // clone is for badMutable plugin
+      const date = this.clone().set(C.DATE, 1).set(u, n + number)
       return date.set(C.DATE, Math.min(this.$D, date.daysInMonth()))
     }
     const instanceFactorySet = (n) => {
@@ -346,6 +352,7 @@ class Dayjs {
   }
 
   locale(preset, object) {
+    if (!preset) return this.$L
     const that = this.clone()
     that.$L = parseLocale(preset, object, true)
     return that
@@ -359,18 +366,6 @@ class Dayjs {
     return new Date(this.$d)
   }
 
-  toArray() {
-    return [
-      this.$y,
-      this.$M,
-      this.$D,
-      this.$H,
-      this.$m,
-      this.$s,
-      this.$ms
-    ]
-  }
-
   toJSON() {
     return this.toISOString()
   }
@@ -382,18 +377,6 @@ class Dayjs {
     return this.$d.toISOString()
   }
 
-  toObject() {
-    return {
-      years: this.$y,
-      months: this.$M,
-      date: this.$D,
-      hours: this.$H,
-      minutes: this.$m,
-      seconds: this.$s,
-      milliseconds: this.$ms
-    }
-  }
-
   toString() {
     return this.$d.toUTCString()
   }
diff --git a/src/locale/zh-cn.js b/src/locale/zh-cn.js
index bc28c7edf..e3e754432 100644
--- a/src/locale/zh-cn.js
+++ b/src/locale/zh-cn.js
@@ -7,7 +7,14 @@ const locale = {
   weekdaysMin: '日_一_二_三_四_五_六'.split('_'),
   months: '一月_二月_三月_四月_五月_六月_七月_八月_九月_十月_十一月_十二月'.split('_'),
   monthsShort: '1月_2月_3月_4月_5月_6月_7月_8月_9月_10月_11月_12月'.split('_'),
-  ordinal: n => `${n}日`,
+  ordinal: (number, period) => {
+    switch (period) {
+      case 'W':
+        return `${number}周`
+      default:
+        return `${number}日`
+    }
+  },
   weekStart: 1,
   formats: {
     LT: 'HH:mm',
diff --git a/src/plugin/advancedFormat/index.js b/src/plugin/advancedFormat/index.js
index 854f2b73b..1b5288c08 100644
--- a/src/plugin/advancedFormat/index.js
+++ b/src/plugin/advancedFormat/index.js
@@ -13,13 +13,16 @@ export default (o, c, d) => { // locale needed later
     const locale = this.$locale()
     const utils = this.$utils()
     const str = formatStr || FORMAT_DEFAULT
-    const result = str.replace(/Q|Do|X|x|k{1,2}|S/g, (match) => {
+    const result = str.replace(/Q|wo|gggg|Do|X|x|k{1,2}|S/g, (match) => {
       switch (match) {
         case 'Q':
           return Math.ceil((this.$M + 1) / 3)
-        case 'Do': {
+        case 'Do':
           return locale.ordinal(this.$D)
-        }
+        case 'gggg':
+          return this.weekYear()
+        case 'wo':
+          return locale.ordinal(this.week(), 'W') // W for week
         case 'k':
         case 'kk':
           return utils.s(String(this.$H === 0 ? 24 : this.$H), match === 'k' ? 1 : 2, '0')
diff --git a/src/plugin/badMutable/index.js b/src/plugin/badMutable/index.js
new file mode 100644
index 000000000..c82aafb67
--- /dev/null
+++ b/src/plugin/badMutable/index.js
@@ -0,0 +1,53 @@
+export default (o, c) => { // locale needed later
+  const proto = c.prototype
+  proto.$g = function (input, get, set) {
+    if (this.$utils().u(input)) return this[get]
+    return this.$set(set, input)
+  }
+
+  proto.set = function (string, int) {
+    return this.$set(string, int)
+  }
+
+  const oldStartOf = proto.startOf
+  proto.startOf = function (units, startOf) {
+    this.$d = oldStartOf.bind(this)(units, startOf).toDate()
+    this.init()
+    return this
+  }
+
+  const oldAdd = proto.add
+  proto.add = function (number, units) {
+    this.$d = oldAdd.bind(this)(number, units).toDate()
+    this.init()
+    return this
+  }
+
+  const oldLocale = proto.locale
+  proto.locale = function (preset, object) {
+    if (!preset) return this.$L
+    this.$L = oldLocale.bind(this)(preset, object).$L
+    return this
+  }
+
+  const oldDaysInMonth = proto.daysInMonth
+  proto.daysInMonth = function () {
+    return oldDaysInMonth.bind(this.clone())()
+  }
+
+  const oldIsSame = proto.isSame
+  proto.isSame = function (that, units) {
+    return oldIsSame.bind(this.clone())(that, units)
+  }
+
+  const oldIsBefore = proto.isBefore
+  proto.isBefore = function (that, units) {
+    return oldIsBefore.bind(this.clone())(that, units)
+  }
+
+  const oldIsAfter = proto.isAfter
+  proto.isAfter = function (that, units) {
+    return oldIsAfter.bind(this.clone())(that, units)
+  }
+}
+
diff --git a/src/plugin/customParseFormat/index.js b/src/plugin/customParseFormat/index.js
index cffbffbbb..0851d4edd 100644
--- a/src/plugin/customParseFormat/index.js
+++ b/src/plugin/customParseFormat/index.js
@@ -1,4 +1,4 @@
-const formattingTokens = /(\[[^[]*\])|([-:/.()\s]+)|(A|a|YYYY|YY?|MM?M?M?|DD?|hh?|HH?|mm?|ss?|S{1,3}|z|ZZ?)/g
+const formattingTokens = /(\[[^[]*\])|([-:/.()\s]+)|(A|a|YYYY|YY?|MM?M?M?|Do|DD?|hh?|HH?|mm?|ss?|S{1,3}|z|ZZ?)/g
 
 const match1 = /\d/ // 0 - 9
 const match2 = /\d\d/ // 00 - 99
@@ -56,6 +56,16 @@ const expressions = {
   hh: [match1to2, addInput('hours')],
   D: [match1to2, addInput('day')],
   DD: [match2, addInput('day')],
+  Do: [matchWord, function (input) {
+    const { ordinal } = locale;
+    [this.day] = input.match(/\d+/)
+    if (!ordinal) return
+    for (let i = 1; i <= 31; i += 1) {
+      if (ordinal(i).replace(/\[|\]/g, '') === input) {
+        this.day = i
+      }
+    }
+  }],
   M: [match1to2, addInput('month')],
   MM: [match2, addInput('month')],
   MMM: [matchWord, function (input) {
diff --git a/src/plugin/isMoment/index.js b/src/plugin/isMoment/index.js
new file mode 100644
index 000000000..05c58f9ea
--- /dev/null
+++ b/src/plugin/isMoment/index.js
@@ -0,0 +1,6 @@
+export default (o, c, f) => {
+  f.isMoment = function (input) {
+    return f.isDayjs(input)
+  }
+}
+
diff --git a/src/plugin/localeData/index.js b/src/plugin/localeData/index.js
new file mode 100644
index 000000000..b85a838a4
--- /dev/null
+++ b/src/plugin/localeData/index.js
@@ -0,0 +1,16 @@
+export default (o, c) => { // locale needed later
+  const proto = c.prototype
+  const localeData = function () {
+    return {
+      months: instance => instance.format('MMMM'),
+      monthsShort: instance => instance.format('MMM'),
+      firstDayOfWeek: () => this.$locale().weekStart || 0,
+      weekdaysMin: instance => instance.format('dd'),
+      weekdaysShort: instance => instance.format('ddd')
+    }
+  }
+  proto.localeData = function () {
+    return localeData.bind(this)()
+  }
+}
+
diff --git a/src/plugin/toArray/index.js b/src/plugin/toArray/index.js
new file mode 100644
index 000000000..9ffc16040
--- /dev/null
+++ b/src/plugin/toArray/index.js
@@ -0,0 +1,15 @@
+export default (o, c) => {
+  const proto = c.prototype
+  proto.toArray = function () {
+    return [
+      this.$y,
+      this.$M,
+      this.$D,
+      this.$H,
+      this.$m,
+      this.$s,
+      this.$ms
+    ]
+  }
+}
+
diff --git a/src/plugin/toObject/index.js b/src/plugin/toObject/index.js
new file mode 100644
index 000000000..08d22d844
--- /dev/null
+++ b/src/plugin/toObject/index.js
@@ -0,0 +1,15 @@
+export default (o, c) => {
+  const proto = c.prototype
+  proto.toObject = function () {
+    return {
+      years: this.$y,
+      months: this.$M,
+      date: this.$D,
+      hours: this.$H,
+      minutes: this.$m,
+      seconds: this.$s,
+      milliseconds: this.$ms
+    }
+  }
+}
+
diff --git a/src/plugin/weekOfYear/index.js b/src/plugin/weekOfYear/index.js
index b7c301361..e2fc9b3e8 100644
--- a/src/plugin/weekOfYear/index.js
+++ b/src/plugin/weekOfYear/index.js
@@ -6,11 +6,12 @@ export default (o, c, d) => {
     if (week !== null) {
       return this.add((week - this.week()) * 7, 'day')
     }
-    const endOfYear = this.endOf(Y)
+    // d(this) clone is for badMutable plugin
+    const endOfYear = d(this).endOf(Y)
     if (endOfYear.day() !== 6 && this.month() === 11 && (31 - this.date()) <= endOfYear.day()) {
       return 1
     }
-    const startOfYear = d(this.$d).startOf(Y)
+    const startOfYear = d(this).startOf(Y)
     const compareDay = startOfYear.subtract(startOfYear.day(), D).subtract(1, MS)
     const diffInWeek = this.diff(compareDay, W, true)
     return Math.ceil(diffInWeek)
diff --git a/src/plugin/weekYear/index.js b/src/plugin/weekYear/index.js
new file mode 100644
index 000000000..1fa7577b7
--- /dev/null
+++ b/src/plugin/weekYear/index.js
@@ -0,0 +1,12 @@
+export default (o, c) => {
+  const proto = c.prototype
+  proto.weekYear = function () {
+    const month = this.month()
+    const weekOfYear = this.week()
+    const year = this.year()
+    if (weekOfYear === 1 && month === 11) {
+      return year + 1
+    }
+    return year
+  }
+}
diff --git a/test/display.test.js b/test/display.test.js
index a8a328688..603a6988b 100644
--- a/test/display.test.js
+++ b/test/display.test.js
@@ -230,10 +230,6 @@ it('As Javascript Date -> toDate', () => {
   expect(jsDate.toUTCString()).not.toBe(base.toString())
 })
 
-it('As Array -> toArray', () => {
-  expect(dayjs().toArray()).toEqual(moment().toArray())
-})
-
 it('As JSON -> toJSON', () => {
   expect(dayjs().toJSON()).toBe(moment().toJSON())
 })
@@ -241,7 +237,3 @@ it('As JSON -> toJSON', () => {
 it('As ISO 8601 String -> toISOString e.g. 2013-02-04T22:44:30.652Z', () => {
   expect(dayjs().toISOString()).toBe(moment().toISOString())
 })
-
-it('As Object -> toObject', () => {
-  expect(dayjs().toObject()).toEqual(moment().toObject())
-})
diff --git a/test/get-set.test.js b/test/get-set.test.js
index af5676a38..7587915cf 100644
--- a/test/get-set.test.js
+++ b/test/get-set.test.js
@@ -12,34 +12,50 @@ afterEach(() => {
 
 it('Year', () => {
   expect(dayjs().year()).toBe(moment().year())
+  expect(dayjs().year(0).valueOf()).toBe(moment().year(0).valueOf())
+  expect(dayjs().year(2000).valueOf()).toBe(moment().year(2000).valueOf())
 })
 
 it('Month', () => {
   expect(dayjs().month()).toBe(moment().month())
+  expect(dayjs().month(0).valueOf()).toBe(moment().month(0).valueOf())
+  expect(dayjs().month(1).valueOf()).toBe(moment().month(1).valueOf())
 })
 
 it('Day of Week', () => {
   expect(dayjs().day()).toBe(moment().day())
+  expect(dayjs().day(0).format()).toBe(moment().day(0).format())
+  expect(dayjs().day(1).format()).toBe(moment().day(1).format())
 })
 
 it('Date', () => {
   expect(dayjs().date()).toBe(moment().date())
+  expect(dayjs().date(0).valueOf()).toBe(moment().date(0).valueOf())
+  expect(dayjs().date(1).valueOf()).toBe(moment().date(1).valueOf())
 })
 
 it('Hour', () => {
   expect(dayjs().hour()).toBe(moment().hour())
+  expect(dayjs().hour(0).valueOf()).toBe(moment().hour(0).valueOf())
+  expect(dayjs().hour(1).valueOf()).toBe(moment().hour(1).valueOf())
 })
 
 it('Minute', () => {
   expect(dayjs().minute()).toBe(moment().minute())
+  expect(dayjs().minute(0).valueOf()).toBe(moment().minute(0).valueOf())
+  expect(dayjs().minute(1).valueOf()).toBe(moment().minute(1).valueOf())
 })
 
 it('Second', () => {
   expect(dayjs().second()).toBe(moment().second())
+  expect(dayjs().second(0).valueOf()).toBe(moment().second(0).valueOf())
+  expect(dayjs().second(1).valueOf()).toBe(moment().second(1).valueOf())
 })
 
 it('Millisecond', () => {
   expect(dayjs().millisecond()).toBe(moment().millisecond())
+  expect(dayjs().millisecond(0).valueOf()).toBe(moment().millisecond(0).valueOf())
+  expect(dayjs().millisecond(1).valueOf()).toBe(moment().millisecond(1).valueOf())
 })
 
 it('Set Day', () => {
diff --git a/test/locale.test.js b/test/locale.test.js
index 06560b6ba..8438bd095 100644
--- a/test/locale.test.js
+++ b/test/locale.test.js
@@ -1,4 +1,5 @@
 import MockDate from 'mockdate'
+import moment from 'moment'
 import dayjs from '../src'
 import es from '../src/locale/es'
 
@@ -44,6 +45,17 @@ it('set global locale', () => {
     .toBe('Saturday 28, April')
 })
 
+it('get instance locale name', () => {
+  expect(dayjs().locale()).toBe('en')
+  expect(dayjs().locale()).toBe(moment().locale())
+  expect(dayjs().locale('es').locale()).toBe('es')
+  expect(dayjs().locale('es').locale()).toBe(moment().locale('es').locale())
+  dayjs.locale(es)
+  moment.locale('es')
+  expect(dayjs().locale()).toBe('es')
+  expect(dayjs().locale()).toBe(moment().locale())
+})
+
 it('immutable instance locale', () => {
   dayjs.locale('en')
   const origin = dayjs('2018-4-28')
diff --git a/test/plugin/advancedFormat.test.js b/test/plugin/advancedFormat.test.js
index 985ff50be..74de4eb9b 100644
--- a/test/plugin/advancedFormat.test.js
+++ b/test/plugin/advancedFormat.test.js
@@ -2,7 +2,12 @@ import MockDate from 'mockdate'
 import moment from 'moment'
 import dayjs from '../../src'
 import advancedFormat from '../../src/plugin/advancedFormat'
+import weekOfYear from '../../src/plugin/weekOfYear'
+import weekYear from '../../src/plugin/weekYear'
+import '../../src/locale/zh-cn'
 
+dayjs.extend(weekYear)
+dayjs.extend(weekOfYear)
 dayjs.extend(advancedFormat)
 
 beforeEach(() => {
@@ -65,3 +70,15 @@ it('Format Hour k kk 24-hour 1 - 24', () => {
   expect(dayjs(d).format('kk')).toBe('23')
   expect(dayjs(d).format('kk')).toBe(moment(d).format('kk'))
 })
+
+it('Format Week of Year wo', () => {
+  const d = '2018-12-01'
+  expect(dayjs(d).format('wo')).toBe(moment(d).format('wo'))
+  expect(dayjs(d).locale('zh-cn').format('wo'))
+    .toBe(moment(d).locale('zh-cn').format('wo'))
+})
+
+it('Format Week Year gggg', () => {
+  const d = '2018-12-31'
+  expect(dayjs(d).format('gggg')).toBe(moment(d).format('gggg'))
+})
diff --git a/test/plugin/badMutable.test.js b/test/plugin/badMutable.test.js
new file mode 100644
index 000000000..5b38bc899
--- /dev/null
+++ b/test/plugin/badMutable.test.js
@@ -0,0 +1,177 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import badMutable from '../../src/plugin/badMutable'
+import '../../src/locale/zh-cn'
+
+dayjs.extend(badMutable)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+describe('Set', () => {
+  it('Setters', () => {
+    const d = dayjs()
+    const m = moment()
+    expect(d.year()).toBe(m.year())
+    d.year(2000)
+    m.year(2000)
+    expect(d.format()).toBe(m.format())
+    d.month(1)
+    m.month(1)
+    expect(d.format()).toBe(m.format())
+    d.day(1)
+    m.day(1)
+    expect(d.format()).toBe(m.format())
+    d.date(1)
+    m.date(1)
+    expect(d.format()).toBe(m.format())
+    d.hour(1)
+    m.hour(1)
+    expect(d.format()).toBe(m.format())
+    d.minute(1)
+    m.minute(1)
+    expect(d.format()).toBe(m.format())
+    d.second(1)
+    m.second(1)
+    expect(d.format()).toBe(m.format())
+    d.millisecond(1)
+    m.millisecond(1)
+    expect(d.format()).toBe(m.format())
+  })
+
+  it('Set', () => {
+    const d = dayjs()
+    const m = moment()
+    d.set('year', 2000)
+    m.set('year', 2000)
+    expect(d.format()).toBe(m.format())
+    d.set('month', 12)
+    m.set('month', 12)
+    expect(d.format()).toBe(m.format())
+    d.set('day', 1)
+    m.set('day', 1)
+    expect(d.format()).toBe(m.format())
+    d.set('date', 1)
+    m.set('date', 1)
+    expect(d.format()).toBe(m.format())
+    d.set('hour', 1)
+    m.set('hour', 1)
+    expect(d.format()).toBe(m.format())
+    d.set('minute', 1)
+    m.set('minute', 1)
+    expect(d.format()).toBe(m.format())
+    d.set('second', 1)
+    m.set('second', 1)
+    expect(d.format()).toBe(m.format())
+    d.set('millisecond', 1)
+    m.set('millisecond', 1)
+    expect(d.format()).toBe(m.format())
+  })
+})
+
+describe('StartOf', () => {
+  it('StartOf', () => {
+    const d = dayjs()
+    const m = moment()
+    d.startOf('year')
+    m.startOf('year')
+    expect(d.format()).toBe(m.format())
+    d.startOf('month')
+    m.startOf('month')
+    expect(d.format()).toBe(m.format())
+    d.startOf('day')
+    m.startOf('day')
+    expect(d.format()).toBe(m.format())
+    d.startOf('date')
+    m.startOf('date')
+    expect(d.format()).toBe(m.format())
+    d.startOf('hour')
+    m.startOf('hour')
+    expect(d.format()).toBe(m.format())
+    d.startOf('minute')
+    m.startOf('minute')
+    expect(d.format()).toBe(m.format())
+    d.startOf('second')
+    m.startOf('second')
+    expect(d.format()).toBe(m.format())
+    d.startOf('millisecond')
+    m.startOf('millisecond')
+    expect(d.format()).toBe(m.format())
+    d.startOf('week')
+    m.startOf('week')
+    expect(d.format()).toBe(m.format())
+  })
+})
+
+describe('Add', () => {
+  it('Add', () => {
+    const d = dayjs()
+    const m = moment()
+    d.add(1, 'year')
+    m.add(1, 'year')
+    expect(d.format()).toBe(m.format())
+    d.add(12, 'month')
+    m.add(12, 'month')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'day')
+    m.add(1, 'day')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'date')
+    m.add(1, 'date')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'hour')
+    m.add(1, 'hour')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'minute')
+    m.add(1, 'minute')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'second')
+    m.add(1, 'second')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'millisecond')
+    m.add(1, 'millisecond')
+    expect(d.format()).toBe(m.format())
+    d.add(1, 'week')
+    m.add(1, 'week')
+    expect(d.format()).toBe(m.format())
+  })
+})
+
+it('daysInMonth', () => {
+  const d = dayjs()
+  const m = moment()
+  expect(d.daysInMonth()).toBe(m.daysInMonth())
+  expect(d.format()).toBe(m.format())
+})
+
+it('Locale', () => {
+  const d = dayjs()
+  const m = moment()
+  const format = 'MMMM'
+  expect(d.locale()).toBe(m.locale())
+  expect(d.format(format)).toBe(m.format(format))
+  d.locale('zh-cn')
+  m.locale('zh-cn')
+  expect(d.locale()).toBe(m.locale())
+  expect(d.format(format)).toBe(m.format(format))
+})
+
+it('isAfter isBefore isSame', () => {
+  const d = dayjs()
+  const format = dayjs().format()
+  d.isSame(dayjs, 'year')
+  expect(d.format()).toBe(format)
+  expect(d.isSame()).toBe(true)
+  d.isBefore(dayjs, 'hour')
+  expect(d.format()).toBe(format)
+  expect(d.isBefore()).toBe(false)
+  d.isAfter(dayjs, 'month')
+  expect(d.format()).toBe(format)
+  expect(d.isAfter()).toBe(false)
+})
diff --git a/test/plugin/customParseFormat.test.js b/test/plugin/customParseFormat.test.js
index eb2f2204b..46286bc66 100644
--- a/test/plugin/customParseFormat.test.js
+++ b/test/plugin/customParseFormat.test.js
@@ -3,6 +3,7 @@ import moment from 'moment'
 import dayjs from '../../src'
 import customParseFormat from '../../src/plugin/customParseFormat'
 import uk from '../../src/locale/uk'
+import '../../src/locale/zh-cn'
 
 dayjs.extend(customParseFormat)
 
@@ -169,3 +170,19 @@ it('correctly parse month from string after changing locale globally', () => {
     moment.locale(momentLocale)
   }
 })
+
+it('correctly parse ordinal', () => {
+  const input = '7th March 2019'
+  const input2 = '17th March 2019'
+  const inputFalse = '7st March 2019'
+  const inputZHCN = '7日 三月 2019'
+  const format = 'Do MMMM YYYY'
+  expect(dayjs(input, format).valueOf())
+    .toBe(moment(input, format).valueOf())
+  expect(dayjs(input2, format).valueOf())
+    .toBe(moment(input2, format).valueOf())
+  expect(dayjs(inputFalse, format).valueOf())
+    .toBe(moment(inputFalse, format).valueOf())
+  expect(dayjs(inputZHCN, format, 'zh-cn').valueOf())
+    .toBe(moment(inputZHCN, format, 'zh-cn').valueOf())
+})
diff --git a/test/plugin/isMoment.test.js b/test/plugin/isMoment.test.js
new file mode 100644
index 000000000..0c83e52ce
--- /dev/null
+++ b/test/plugin/isMoment.test.js
@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import isMoment from '../../src/plugin/isMoment'
+
+dayjs.extend(isMoment)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('IsLeapYear', () => {
+  expect(dayjs.isMoment(dayjs())).toBe(true)
+  expect(dayjs.isMoment(new Date())).toBe(false)
+})
diff --git a/test/plugin/localeData.test.js b/test/plugin/localeData.test.js
new file mode 100644
index 000000000..5e5e1cb95
--- /dev/null
+++ b/test/plugin/localeData.test.js
@@ -0,0 +1,26 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import localeData from '../../src/plugin/localeData'
+
+dayjs.extend(localeData)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('localeData', () => {
+  const d = dayjs()
+  const m = moment()
+  const dayjsLocaleData = dayjs().localeData()
+  const momentLocaleData = moment().localeData()
+  expect(dayjsLocaleData.firstDayOfWeek()).toBe(momentLocaleData.firstDayOfWeek())
+  expect(dayjsLocaleData.months(d)).toBe(momentLocaleData.months(m))
+  expect(dayjsLocaleData.monthsShort(d)).toBe(momentLocaleData.monthsShort(m))
+  expect(dayjsLocaleData.weekdaysMin(d)).toBe(momentLocaleData.weekdaysMin(m))
+  expect(dayjsLocaleData.weekdaysShort(d)).toBe(momentLocaleData.weekdaysShort(m))
+})
diff --git a/test/plugin/toArray.test.js b/test/plugin/toArray.test.js
new file mode 100644
index 000000000..674c76f97
--- /dev/null
+++ b/test/plugin/toArray.test.js
@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import toArray from '../../src/plugin/toArray'
+
+dayjs.extend(toArray)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('As Array -> toArray', () => {
+  expect(dayjs().toArray()).toEqual(moment().toArray())
+})
diff --git a/test/plugin/toObject.test.js b/test/plugin/toObject.test.js
new file mode 100644
index 000000000..3d0c21335
--- /dev/null
+++ b/test/plugin/toObject.test.js
@@ -0,0 +1,18 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import toObject from '../../src/plugin/toObject'
+
+dayjs.extend(toObject)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('As Object -> toObject', () => {
+  expect(dayjs().toObject()).toEqual(moment().toObject())
+})
diff --git a/test/plugin/weekYear.test.js b/test/plugin/weekYear.test.js
new file mode 100644
index 000000000..a23709e50
--- /dev/null
+++ b/test/plugin/weekYear.test.js
@@ -0,0 +1,30 @@
+import moment from 'moment'
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import weekYear from '../../src/plugin/weekYear'
+import weekOfYear from '../../src/plugin/weekOfYear'
+
+dayjs.extend(weekYear)
+dayjs.extend(weekOfYear)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('Week Year', () => {
+  const daySet = [
+    ['2018-12-01', 2018],
+    ['2018-12-30', 2019],
+    ['2018-12-31', 2019],
+    ['2019-01-01', 2019]
+  ]
+  daySet.forEach((d) => {
+    const [day, result] = d
+    expect(dayjs(day).weekYear()).toBe(result)
+    expect(dayjs(day).weekYear()).toBe(moment(day).weekYear())
+  })
+})
diff --git a/types/index.d.ts b/types/index.d.ts
index 22ea11726..eee848e61 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -12,16 +12,6 @@ declare namespace dayjs {
   type OpUnitTypeShort = 'w'
   export type OpUnitType = UnitType | "week" | OpUnitTypeShort;
 
-  interface DayjsObject {
-    years: number
-    months: number
-    date: number
-    hours: number
-    minutes: number
-    seconds: number
-    milliseconds: number
-  }
-
   class Dayjs {
     constructor (config?: ConfigType)
 
@@ -31,20 +21,36 @@ declare namespace dayjs {
 
     year(): number
 
+    year(value: number): Dayjs
+
     month(): number
 
+    month(value: number): Dayjs
+
     date(): number
 
+    date(value: number): Dayjs
+
     day(): number
 
+    day(value: number): Dayjs
+
     hour(): number
 
+    hour(value: number): Dayjs
+
     minute(): number
 
+    minute(value: number): Dayjs
+
     second(): number
 
+    second(value: number): Dayjs
+
     millisecond(): number
 
+    millisecond(value: number): Dayjs
+
     set(unit: UnitType, value: number): Dayjs
 
     add(value: number, unit: OpUnitType): Dayjs
@@ -67,14 +73,10 @@ declare namespace dayjs {
 
     toDate(): Date
 
-    toArray(): number[]
-
     toJSON(): string
 
     toISOString(): string
 
-    toObject(): DayjsObject
-
     toString(): string
 
     utcOffset(): number
@@ -85,6 +87,8 @@ declare namespace dayjs {
 
     isAfter(date: ConfigType, unit?: OpUnitType): boolean
 
+    locale(): string
+
     locale(preset: string | { name: string, [key: string]: any }, object?: { [key: string]: any }): Dayjs
   }
 
diff --git a/types/plugin/badMutable.d.ts b/types/plugin/badMutable.d.ts
new file mode 100644
index 000000000..30ec75e5d
--- /dev/null
+++ b/types/plugin/badMutable.d.ts
@@ -0,0 +1,4 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
diff --git a/types/plugin/isMoment.d.ts b/types/plugin/isMoment.d.ts
new file mode 100644
index 000000000..dac24f6f7
--- /dev/null
+++ b/types/plugin/isMoment.d.ts
@@ -0,0 +1,10 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs' {
+
+  export function isMoment(input: any): boolean
+
+}
diff --git a/types/plugin/localeData.d.ts b/types/plugin/localeData.d.ts
new file mode 100644
index 000000000..7d9817637
--- /dev/null
+++ b/types/plugin/localeData.d.ts
@@ -0,0 +1,10 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs' {
+  interface Dayjs {
+    localeData(): any
+  }
+}
diff --git a/types/plugin/toArray.d.ts b/types/plugin/toArray.d.ts
new file mode 100644
index 000000000..45f1f0c3c
--- /dev/null
+++ b/types/plugin/toArray.d.ts
@@ -0,0 +1,10 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs' {
+  interface Dayjs {
+    toArray(): number[]
+  }
+}
diff --git a/types/plugin/toObject.d.ts b/types/plugin/toObject.d.ts
new file mode 100644
index 000000000..ca12aaf00
--- /dev/null
+++ b/types/plugin/toObject.d.ts
@@ -0,0 +1,20 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+interface DayjsObject {
+  years: number
+  months: number
+  date: number
+  hours: number
+  minutes: number
+  seconds: number
+  milliseconds: number
+}
+
+declare module 'dayjs' {
+  interface Dayjs {
+    toObject(): DayjsObject
+  }
+}
diff --git a/types/plugin/weekOfYear.d.ts b/types/plugin/weekOfYear.d.ts
index 360219556..d98801455 100644
--- a/types/plugin/weekOfYear.d.ts
+++ b/types/plugin/weekOfYear.d.ts
@@ -6,5 +6,7 @@ export = plugin
 declare module 'dayjs' {
   interface Dayjs {
     week(): number
+
+    week(value : number): Dayjs
   }
 }
diff --git a/types/plugin/weekYear.d.ts b/types/plugin/weekYear.d.ts
new file mode 100644
index 000000000..df2533123
--- /dev/null
+++ b/types/plugin/weekYear.d.ts
@@ -0,0 +1,10 @@
+import { PluginFunc } from 'dayjs'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs' {
+  interface Dayjs {
+    weekYear(): number
+  }
+}