fix: Add WeekYear plugin

src/locale/zh-cn.js

@@ -7,7 +7,6 @@ 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('_'),
-  ordinal1: n => `${n}日`,
   ordinal: (number, period) => {
     switch (period) {
       case 'W':

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
+  }
+}

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())
+  })
+})

types/plugin/weekOfYear.d.ts

@@ -6,5 +6,7 @@ export = plugin
 declare module 'dayjs' {
   interface Dayjs {
     week(): number
+
+    week(value : number): Dayjs
   }
 }

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
+  }
+}