feat: add check leap year algorithm

Maths/CheckLeapYear.js

@@ -0,0 +1,20 @@
+/**
+ * @function checkLeapYear
+ * @description A leap year is a year that is divisible by 4, except for
+ *   century years which must be divisible by 400. This function checks
+ *   whether a given year is a leap year.
+ * @param {number} year - A positive integer representing a year
+ * @returns {boolean} - True if the year is a leap year, false otherwise
+ * @see https://en.wikipedia.org/wiki/Leap_year
+ * @example checkLeapYear(2000) => true
+ * @example checkLeapYear(1900) => false
+ * @example checkLeapYear(2024) => true
+ */
+const checkLeapYear = (year) => {
+  if (!Number.isInteger(year) || year < 1) {
+    throw new TypeError('Input must be a positive integer')
+  }
+  return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0
+}
+
+export { checkLeapYear }

Maths/test/CheckLeapYear.test.js

@@ -0,0 +1,47 @@
+import { checkLeapYear } from '../CheckLeapYear.js'
+
+describe('checkLeapYear', () => {
+  test('2000 is a leap year', () => {
+    expect(checkLeapYear(2000)).toBe(true)
+  })
+
+  test('1900 is NOT a leap year', () => {
+    expect(checkLeapYear(1900)).toBe(false)
+  })
+
+  test('2024 is a leap year', () => {
+    expect(checkLeapYear(2024)).toBe(true)
+  })
+
+  test('2023 is NOT a leap year', () => {
+    expect(checkLeapYear(2023)).toBe(false)
+  })
+
+  test('1600 is a leap year', () => {
+    expect(checkLeapYear(1600)).toBe(true)
+  })
+
+  test('1700 is NOT a leap year', () => {
+    expect(checkLeapYear(1700)).toBe(false)
+  })
+
+  test('2100 is NOT a leap year', () => {
+    expect(checkLeapYear(2100)).toBe(false)
+  })
+
+  test('400 is a leap year', () => {
+    expect(checkLeapYear(400)).toBe(true)
+  })
+
+  test('throws TypeError for zero', () => {
+    expect(() => checkLeapYear(0)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for negative input', () => {
+    expect(() => checkLeapYear(-4)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for float input', () => {
+    expect(() => checkLeapYear(2024.5)).toThrow(TypeError)
+  })
+})