fix: Fix WeekOfYear Plugin wrong calender week number bug

fix #760

Author: iamkun

src/plugin/weekOfYear/index.js

@@ -6,25 +6,14 @@ export default (o, c, d) => {
     if (week !== null) {
       return this.add((week - this.week()) * 7, 'day')
     }
-
     const weekStart = this.$locale().weekStart || 0
-
-    // d(this) clone is for badMutable plugin
-    const endOfYear = d(this).endOf(Y)
-    if (
-      weekStart === 0 &&
-      endOfYear.day() !== 6 &&
-      this.month() === 11 &&
-      31 - this.date() <= endOfYear.day()
-    ) {
-      return 1
-    }
-
     const startOfYear = d(this).startOf(Y)
     const compareDay = startOfYear.subtract(startOfYear.day() - weekStart, D).subtract(1, MS)
     const diffInWeek = this.diff(compareDay, W, true)
-    return Math.ceil(diffInWeek)
+    const result = Math.ceil(diffInWeek)
+    return result > 52 ? 1 : result
   }
+
   proto.weeks = function (week = null) {
     return this.week(week)
   }

test/plugin/weekOfYear.test.js

@@ -40,6 +40,7 @@ it('Week of year with locale', () => {
   // Edges
   expect(dayjs('2018-12-30').week()).toBe(moment('2018-12-30').week())
   expect(dayjs('2019-12-29').week()).toBe(moment('2019-12-29').week())
+  expect(dayjs('2019-12-30').week()).toBe(moment('2019-12-30').week())
 })
 
 it('Format w ww wo', () => {