refactor: use isLeapYear (#1638)

Author: vil02

Diff for: Conversions/DateDayDifference.js

@@ -6,13 +6,8 @@
     Algorithm & Explanation : https://ncalculators.com/time-date/date-difference-calculator.htm
 */
 
-// Internal method for make calculations easier
-const isLeap = (year) => {
-  if (year % 400 === 0) return true
-  else if (year % 100 === 0) return false
-  else if (year % 4 === 0) return true
-  else return false
-}
+import { isLeapYear } from '../Maths/LeapYear'
+
 const DateToDay = (dd, mm, yyyy) => {
   return (
     365 * (yyyy - 1) +
@@ -21,7 +16,7 @@ const DateToDay = (dd, mm, yyyy) => {
     Math.floor((yyyy - 1) / 400) +
     dd +
     Math.floor((367 * mm - 362) / 12) +
-    (mm <= 2 ? 0 : isLeap(yyyy) ? -1 : -2)
+    (mm <= 2 ? 0 : isLeapYear(yyyy) ? -1 : -2)
   )
 }
 

Diff for: Timing-Functions/GetMonthDays.js

@@ -6,6 +6,8 @@
   e.g.: mahfoudh.arous.com ->false
 */
 
+import { isLeapYear } from '../Maths/LeapYear'
+
 const getMonthDays = (monthNumber, year) => {
   const the31DaysMonths = [1, 3, 5, 7, 8, 10, 12]
   const the30DaysMonths = [4, 6, 9, 11]
@@ -26,11 +28,8 @@ const getMonthDays = (monthNumber, year) => {
     return 30
   }
 
-  // Check for Leap year
-  if (year % 4 === 0) {
-    if (year % 100 !== 0 || (year % 100 === 0 && year % 400 === 0)) {
-      return 29
-    }
+  if (isLeapYear(year)) {
+    return 29
   }
 
   return 28

Diff for: Timing-Functions/test/GetMonthDays.test.js

@@ -1,16 +1,33 @@
 import { getMonthDays } from '../GetMonthDays'
 
 describe('Get the Days of a Month', () => {
-  it('expects to return 28', () => {
-    expect(getMonthDays(2, 2018)).toEqual(28)
-  })
-
-  it('expects to return 30', () => {
-    expect(getMonthDays(6, 254)).toEqual(30)
-  })
-
-  it('expects to return 29', () => {
-    expect(getMonthDays(2, 2024)).toEqual(29)
+  it.each([
+    [1, 2024, 31],
+    [2, 2024, 29],
+    [3, 2024, 31],
+    [4, 2024, 30],
+    [5, 2024, 31],
+    [6, 2024, 30],
+    [7, 2024, 31],
+    [8, 2024, 31],
+    [9, 2024, 30],
+    [10, 2024, 31],
+    [11, 2024, 30],
+    [12, 2024, 31],
+    [1, 2023, 31],
+    [2, 2023, 28],
+    [3, 2023, 31],
+    [4, 2023, 30],
+    [5, 2023, 31],
+    [6, 2023, 30],
+    [7, 2023, 31],
+    [8, 2023, 31],
+    [9, 2023, 30],
+    [10, 2023, 31],
+    [11, 2023, 30],
+    [12, 2023, 31]
+  ])('Month %i in year %i has %i days', (month, year, expected) => {
+    expect(getMonthDays(month, year)).toBe(expected)
   })
 
   it('expects to throw a type error', () => {