refactoring prevousDay and nextDay functions

src/nextDay/index.ts

@@ -4,7 +4,6 @@ import addDays from '../addDays'
 import toDate from '../toDate'
 import { Day } from '../types'
 
-const baseMap = [7, 6, 5, 4, 3, 2, 1]
 
 /**
  * @name nextDay
@@ -14,7 +13,7 @@ const baseMap = [7, 6, 5, 4, 3, 2, 1]
  * @description
  * When is the next day of the week? 0-6 the day of the week, 0 represents Sunday.
  *
- * @param {Date | number} date - the date to check
+ * @param {Date | number} dirtyDate - the date to check
  * @param {Day} day - day of the week
  * @returns {Date} - the date is the next day of week
  * @throws {TypeError} - 2 arguments required
@@ -29,18 +28,12 @@ const baseMap = [7, 6, 5, 4, 3, 2, 1]
  * const result = nextDay(new Date(2020, 2, 21), 2)
  * //=> Tue Mar 24 2020 00:00:00
  */
-export default function nextDay(date: Date | number, day: Day): Date {
+export default function nextDay(dirtyDate: Date | number, day: Day): Date {
   requiredArgs(2, arguments)
-  const map = genMap(day)
-  return addDays(toDate(date), map[getDay(toDate(date))])
-}
+  const date = toDate(dirtyDate)
+
+  let delta = day - getDay(date) 
+  if(delta<=0) delta += 7
 
-function genMap(daysToMove: number): number[] {
-  if (daysToMove === 0) {
-    return baseMap
-  } else {
-    const mapStart = baseMap.slice(-daysToMove)
-    const mapEnd = baseMap.slice(0, baseMap.length - daysToMove)
-    return mapStart.concat(mapEnd)
-  }
+  return addDays(date, delta)
 }

src/previousDay/index.ts

@@ -4,7 +4,6 @@ import subDays from '../subDays'
 import toDate from '../toDate'
 import { Day } from '../types'
 
-const baseMap = [1,2,3,4,5,6,7]
 
 /**
  * @name previousDay
@@ -14,7 +13,7 @@ const baseMap = [1,2,3,4,5,6,7]
  * @description
  * When is the previous day of the week? 0-6 the day of the week, 0 represents Sunday.
  *
- * @param {Date | number} date - the date to check
+ * @param {Date | number} dirtyDate - the date to check
  * @param {Day} day - day of the week
  * @returns {Date} - the date is the previous day of week
  * @throws {TypeError} - 2 arguments required
@@ -29,18 +28,12 @@ const baseMap = [1,2,3,4,5,6,7]
  * const result = previousDay(new Date(2020, 2, 21), 2)
  * //=> Tue Mar 17 2020 00:00:00
  */
-export default function previousDay(date: Date | number, day: Day): Date {
+export default function previousDay(dirtyDate: Date | number, day: Day): Date {
   requiredArgs(2, arguments)
-  const map = genMap(day+1)
-  return subDays(toDate(date), map[getDay(toDate(date))])
-}
+  const date = toDate(dirtyDate)
+
+  let delta = getDay(date) - day
+  if (delta <= 0) delta += 7
 
-function genMap(daysToMove: number): number[] {
-  if (daysToMove === 0) {
-    return baseMap
-  } else {
-    const mapStart = baseMap.slice(-daysToMove)
-    const mapEnd = baseMap.slice(0, baseMap.length - daysToMove)
-    return mapStart.concat(mapEnd)
-  }
+  return subDays(date, delta)
 }

src/previousDay/test.ts

@@ -73,7 +73,7 @@ describe('previousDay', function () {
     )
   })
 
-  it('returns previours Sunday given the day is Sunday', function () {
+  it('returns previous Sunday given the day is Sunday', function () {
     assert.deepStrictEqual(
       previousDay(new Date(2021, 5 /* Jun */, 27), 0),
       new Date(2021, 5 /* Jun */, 20)

src/previousFriday/test.ts

@@ -2,43 +2,43 @@
 /* eslint-env mocha */
 
 import assert from 'power-assert'
-import previoursFriday from '.'
+import previousFriday from '.'
 
-describe('previoursFriday', function () {
+describe('previousFriday', function () {
   it('returns the following Friday given various dates after the same', function () {
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 5)),
+      previousFriday(new Date(2021, 5 /* Jun */, 5)),
       new Date(2021, 5 /* Jun */, 4)
     )
 
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 6)),
+      previousFriday(new Date(2021, 5 /* Jun */, 6)),
       new Date(2021, 5 /* Jun */, 4)
     )
 
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 11)),
+      previousFriday(new Date(2021, 5 /* Jun */, 11)),
       new Date(2021, 5 /* Jun */, 4)
     )
 
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 14)),
+      previousFriday(new Date(2021, 5 /* Jun */, 14)),
       new Date(2021, 5 /* Jun */, 11)
     )
 
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 15)),
+      previousFriday(new Date(2021, 5 /* Jun */, 15)),
       new Date(2021, 5 /* Jun */, 11)
     )
 
     assert.deepStrictEqual(
-      previoursFriday(new Date(2021, 5 /* Jun */, 24)),
+      previousFriday(new Date(2021, 5 /* Jun */, 24)),
       new Date(2021, 5 /* Jun */, 18)
     )
 
   })
 
   it('returns `Invalid Date` if the given date is invalid', function () {
-    assert(previoursFriday(new Date(NaN)) instanceof Date)
+    assert(previousFriday(new Date(NaN)) instanceof Date)
   })
 })

src/previousMonday/test.ts

@@ -2,43 +2,43 @@
 /* eslint-env mocha */
 
 import assert from 'power-assert'
-import previoursMonday from '.'
+import previousMonday from '.'
 
-describe('previoursMonday', function () {
+describe('previousMonday', function () {
   it('returns the following Monday given various dates after the same', function () {
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 5)),
+      previousMonday(new Date(2021, 5 /* Jun */, 5)),
       new Date(2021, 4 /* May */, 31)
     )
 
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 6)),
+      previousMonday(new Date(2021, 5 /* Jun */, 6)),
       new Date(2021, 4 /* May */, 31)
     )
 
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 7)),
+      previousMonday(new Date(2021, 5 /* Jun */, 7)),
       new Date(2021, 4 /* May */, 31)
     )
 
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 14)),
+      previousMonday(new Date(2021, 5 /* Jun */, 14)),
       new Date(2021, 5 /* Jun */, 7)
     )
 
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 15)),
+      previousMonday(new Date(2021, 5 /* Jun */, 15)),
       new Date(2021, 5 /* Jun */, 14)
     )
 
     assert.deepStrictEqual(
-      previoursMonday(new Date(2021, 5 /* Jun */, 16)),
+      previousMonday(new Date(2021, 5 /* Jun */, 16)),
       new Date(2021, 5 /* Jun */, 14)
     )
 
   })
 
   it('returns `Invalid Date` if the given date is invalid', function () {
-    assert(previoursMonday(new Date(NaN)) instanceof Date)
+    assert(previousMonday(new Date(NaN)) instanceof Date)
   })
 })

src/previousSaturday/test.ts

@@ -2,43 +2,43 @@
 /* eslint-env mocha */
 
 import assert from 'power-assert'
-import previoursSaturday from '.'
+import previousSaturday from '.'
 
-describe('previoursSaturday', function () {
+describe('previousSaturday', function () {
   it('returns the following Saturday given various dates after the same', function () {
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 7)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 7)),
       new Date(2021, 5 /* Jun */, 5)
     )
 
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 8)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 8)),
       new Date(2021, 5 /* Jun */, 5)
     )
 
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 12)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 12)),
       new Date(2021, 5 /* Jun */, 5)
     )
 
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 16)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 16)),
       new Date(2021, 5 /* Jun */, 12)
     )
 
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 17)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 17)),
       new Date(2021, 5 /* Jun */, 12)
     )
 
     assert.deepStrictEqual(
-      previoursSaturday(new Date(2021, 5 /* Jun */, 24)),
+      previousSaturday(new Date(2021, 5 /* Jun */, 24)),
       new Date(2021, 5 /* Jun */, 19)
     )
 
   })
 
   it('returns `Invalid Date` if the given date is invalid', function () {
-    assert(previoursSaturday(new Date(NaN)) instanceof Date)
+    assert(previousSaturday(new Date(NaN)) instanceof Date)
   })
 })

src/previousSunday/test.ts

@@ -2,43 +2,43 @@
 /* eslint-env mocha */
 
 import assert from 'power-assert'
-import previoursSunday from '.'
+import previousSunday from '.'
 
-describe('previoursSunday', function () {
+describe('previousSunday', function () {
   it('returns the following Sunday given various dates after the same', function () {
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 7)),
+      previousSunday(new Date(2021, 5 /* Jun */, 7)),
       new Date(2021, 5 /* Jun */, 6)
     )
 
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 8)),
+      previousSunday(new Date(2021, 5 /* Jun */, 8)),
       new Date(2021, 5 /* Jun */, 6)
     )
 
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 13)),
+      previousSunday(new Date(2021, 5 /* Jun */, 13)),
       new Date(2021, 5 /* Jun */, 6)
     )
 
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 16)),
+      previousSunday(new Date(2021, 5 /* Jun */, 16)),
       new Date(2021, 5 /* Jun */, 13)
     )
 
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 17)),
+      previousSunday(new Date(2021, 5 /* Jun */, 17)),
       new Date(2021, 5 /* Jun */, 13)
     )
 
     assert.deepStrictEqual(
-      previoursSunday(new Date(2021, 5 /* Jun */, 24)),
+      previousSunday(new Date(2021, 5 /* Jun */, 24)),
       new Date(2021, 5 /* Jun */, 20)
     )
 
   })
 
   it('returns `Invalid Date` if the given date is invalid', function () {
-    assert(previoursSunday(new Date(NaN)) instanceof Date)
+    assert(previousSunday(new Date(NaN)) instanceof Date)
   })
 })

src/previousThursday/test.ts

@@ -2,43 +2,43 @@
 /* eslint-env mocha */
 
 import assert from 'power-assert'
-import previoursThursday from '.'
+import previousThursday from '.'
 
-describe('previoursThursday', function () {
+describe('previousThursday', function () {
   it('returns the following Thursday given various dates after the same', function () {
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 5)),
+      previousThursday(new Date(2021, 5 /* Jun */, 5)),
       new Date(2021, 5 /* Jun */, 3)
     )
 
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 6)),
+      previousThursday(new Date(2021, 5 /* Jun */, 6)),
       new Date(2021, 5 /* Jun */, 3)
     )
 
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 10)),
+      previousThursday(new Date(2021, 5 /* Jun */, 10)),
       new Date(2021, 5 /* Jun */, 3)
     )
 
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 14)),
+      previousThursday(new Date(2021, 5 /* Jun */, 14)),
       new Date(2021, 5 /* Jun */, 10)
     )
 
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 15)),
+      previousThursday(new Date(2021, 5 /* Jun */, 15)),
       new Date(2021, 5 /* Jun */, 10)
     )
 
     assert.deepStrictEqual(
-      previoursThursday(new Date(2021, 5 /* Jun */, 24)),
+      previousThursday(new Date(2021, 5 /* Jun */, 24)),
       new Date(2021, 5 /* Jun */, 17)
     )
 
   })
 
   it('returns `Invalid Date` if the given date is invalid', function () {
-    assert(previoursThursday(new Date(NaN)) instanceof Date)
+    assert(previousThursday(new Date(NaN)) instanceof Date)
   })
 })