feat(localDate): add dayOfWeek (#21)

src/datetime/localDate.test.ts

@@ -297,3 +297,14 @@ test('parse weird input', () => {
   expect(LocalDate.parseOrNull(Date.now() as any)).toBeNull()
   expect(LocalDate.parseOrNull((() => {}) as any)).toBeNull()
 })
+
+test('dayOfWeek', () => {
+  expect(localDate('1984-06-18').dayOfWeek()).toBe(1)
+  expect(localDate('1984-06-19').dayOfWeek()).toBe(2)
+  expect(localDate('1984-06-20').dayOfWeek()).toBe(3)
+  expect(localDate('1984-06-21').dayOfWeek()).toBe(4)
+  expect(localDate('1984-06-22').dayOfWeek()).toBe(5)
+  expect(localDate('1984-06-23').dayOfWeek()).toBe(6)
+  expect(localDate('1984-06-24').dayOfWeek()).toBe(7)
+  expect(localDate('1984-06-25').dayOfWeek()).toBe(1)
+})

src/datetime/localDate.ts

@@ -9,7 +9,7 @@ import type {
   UnixTimestampMillisNumber,
   UnixTimestampNumber,
 } from '../types'
-import { LocalTime } from './localTime'
+import { ISODayOfWeek, LocalTime } from './localTime'
 
 export type LocalDateUnit = LocalDateUnitStrict | 'week'
 export type LocalDateUnitStrict = 'year' | 'month' | 'day'
@@ -177,6 +177,10 @@ export class LocalDate {
     return v === undefined ? this.$day : this.set('day', v)
   }
 
+  dayOfWeek(): ISODayOfWeek {
+    return (this.toDate().getDay() || 7) as ISODayOfWeek
+  }
+
   isSame(d: LocalDateInput): boolean {
     d = LocalDate.of(d)
     return this.$day === d.$day && this.$month === d.$month && this.$year === d.$year