locally changing locale is immutable, docs update

README.md

@@ -1,4 +1,4 @@
-English | [简体中文](./README.zh-CN.md) | [日本語](./docs/ja/README-ja.md) | [Português Brasileiro](./docs/pt-br/README-pt-br.md)
+English | [简体中文](./docs/zh-cn/README.zh-CN.md) | [日本語](./docs/ja/README-ja.md) | [Português Brasileiro](./docs/pt-br/README-pt-br.md)
 
 <p align="center"><a href="#" target="_blank" rel="noopener noreferrer"><img width="550"
                                                                              src="https://user-images.githubusercontent.com/17680888/39081119-3057bbe2-456e-11e8-862c-646133ad4b43.png"

docs/en/I18n.md

@@ -31,7 +31,7 @@ dayjs.locale(customizedLocaleObject) // use customize locale
 
 #### Changing locales locally
 
-* Returns CURRENT `Dayjs` object.
+* Returns a new `Dayjs` object by switching to new locale.
 
 Exactly the same as `dayjs#locale`, but only use locale in a specific instance.
 

docs/ja/README-ja.md

@@ -1,5 +1,3 @@
-[English](../../README.md) | [简体中文](../../README.zh-CN.md) | 日本語
-
 <p align="center"><a href="#" target="_blank" rel="noopener noreferrer"><img width="550"
                                                                              src="https://user-images.githubusercontent.com/17680888/39081119-3057bbe2-456e-11e8-862c-646133ad4b43.png"
                                                                              alt="Day.js"></a></p>

docs/pt-br/README-pt-br.md

@@ -1,5 +1,3 @@
-[English](../../README.md) | [简体中文](../../README.zh-CN.md) | Português Brasileiro
-
 <p align="center"><a href="#" target="_blank" rel="noopener noreferrer"><img width="550"
                                                                              src="https://user-images.githubusercontent.com/17680888/39081119-3057bbe2-456e-11e8-862c-646133ad4b43.png"
                                                                              alt="Day.js"></a></p>

docs/zh-cn/I18n.md

@@ -29,9 +29,9 @@ dayjs.locale(customizedLocaleObject) // 使用自定义语言
 
 * 改变全局语言并不会影响在此之前生成的实例
 
-#### 改变局部语言
+#### 改变当前实例的语言
 
-* 返回 **当前** `Dayjs` 对象
+* 改变语言并返回新的`Dayjs` 对象
 
 用法与`dayjs#locale`一致, 但只影响当前实例的语言设置
 

README.zh-CN.md → docs/zh-cn/README.zh-CN.md

@@ -1,5 +1,3 @@
-[English](./README.md) | 简体中文 | [日本語](./docs/ja/README-ja.md) | [Português Brasileiro](./docs/pt-br/README-pt-br.md)
-
 <p align="center"><a href="#" target="_blank" rel="noopener noreferrer"><img width="550"
                                                                              src="https://user-images.githubusercontent.com/17680888/39081119-3057bbe2-456e-11e8-862c-646133ad4b43.png"
                                                                              alt="Day.js"></a></p>
@@ -45,7 +43,7 @@ dayjs().startOf('month').add(1, 'day').set('year', 2018).format('YYYY-MM-DD HH:m
 npm install dayjs --save
 ```
 
-📚[安装指南](./docs/zh-cn/Installation.md)
+📚[安装指南](./Installation.md)
 
 ### API
 
@@ -63,7 +61,7 @@ dayjs().add(1, 'year') // 处理
 dayjs().isBefore(dayjs()) // 查询
 ```
 
-📚[API 参考](./docs/zh-cn/API-reference.md)
+📚[API 参考](./API-reference.md)
 
 ### 国际化 I18n
 
@@ -78,7 +76,7 @@ dayjs.locale('es') // 全局使用西班牙语
 
 dayjs('2018-05-05').locale('zh-cn').format() // 在这个实例上使用简体中文
 ```
-📚[国际化 I18n](./docs/zh-cn/I18n.md)
+📚[国际化 I18n](./I18n.md)
 
 ### 插件
 
@@ -91,7 +89,7 @@ dayjs.extend(AdvancedFormat) // 使用插件
 
 dayjs().format('Q Do k kk X x') // 使用扩展后的API
 ```
-📚[插件列表](./docs/zh-cn/Plugin.md)
+📚[插件列表](./Plugin.md)
 
 ## 开源协议
 

src/index.js

@@ -376,8 +376,9 @@ class Dayjs {
   }
 
   locale(preset, object) {
-    this.$L = parseLocale(preset, object, true)
-    return this
+    const that = this.clone()
+    that.$L = parseLocale(preset, object, true)
+    return that
   }
 
   clone() {

src/plugin/advancedFormat.js

@@ -3,13 +3,10 @@ import { FORMAT_DEFAULT } from '../constant'
 export default (o, c, d) => { // locale needed later
   const proto = c.prototype
   const oldFormat = proto.format
-  // eslint-disable-next-line no-nested-ternary
   d.en.ordinal = (number) => {
-    let suffix = 'th'
-    if (![11, 12].includes(number)) {
-      suffix = ['st', 'nd', 'rd'][(number % 10) - 1] || suffix
-    }
-    return `${number}[${suffix}]`
+    const s = ['th', 'st', 'nd', 'rd']
+    const v = number % 100
+    return `[${number}${(s[(v - 20) % 10] || s[v] || s[0])}]`
   }
   // extend en locale here
   proto.format = function (formatStr, localeObject) {

test/locale.test.js

@@ -49,6 +49,20 @@ it('set global locale', () => {
     .toBe('Saturday 28, April')
 })
 
+it('immutable instance locale', () => {
+  dayjs.locale('en')
+  const origin = dayjs('2018-4-28')
+  expect(origin.format(format))
+    .toBe('Saturday 28, April')
+  expect(origin.locale('es').format(format))
+    .toBe('Sábado 28, Abril')
+  const changed = origin.locale('es')
+  expect(changed.format(format))
+    .toBe('Sábado 28, Abril')
+  expect(origin.format(format))
+    .toBe('Saturday 28, April')
+})
+
 it('User custom locale', () => {
   expect(dayjs('2018-4-28')
     .locale('xx', {

test/plugin/advancedFormat.test.js

@@ -38,6 +38,10 @@ it('Format Day of Month Do 1 - 31', () => {
   expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
   d = '2018-05-11'
   expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
+  d = '2018-05-12'
+  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
+  d = '2018-05-13'
+  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
   d = '2018-05-22'
   expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
 })