feat: add number of digits algorithm

Maths/NumberOfDigits.js

@@ -1,23 +1,18 @@
 /**
- *
- * Author: dephraiim
- * License: GPL-3.0 or later
- *
- * Returns the number of digits of a given integer
- *
+ * @function numberOfDigits
+ * @description Counts the number of digits in a given integer.
+ * @param {number} n - An integer
+ * @returns {number} - The number of digits in n
+ * @see https://en.wikipedia.org/wiki/Numerical_digit
+ * @example numberOfDigits(123) => 3
+ * @example numberOfDigits(0) => 1
+ * @example numberOfDigits(-9999) => 4
  */
+const numberOfDigits = (n) => {
+  if (!Number.isInteger(n)) {
+    throw new TypeError('Input must be an integer')
+  }
+  return Math.abs(n).toString().length
+}
 
-const numberOfDigit = (n) => Math.abs(n).toString().length
-
-/**
- * Returns the number of digits of a given integer.
- *
- * @param {number} n - The integer for which to count digits.
- * @returns {number} The number of digits in the integer.
- * @see https://math.stackexchange.com/questions/2145480/how-does-the-logarithm-returns-the-number-of-digits-of-a-number
- * @author dev-madhurendra
- */
-const numberOfDigitsUsingLog = (n) =>
-  n === 0 ? 1 : Math.floor(Math.log10(Math.abs(n))) + 1
-
-export { numberOfDigit, numberOfDigitsUsingLog }
+export { numberOfDigits }

Maths/test/NumberOfDigits.test.js

@@ -1,23 +1,43 @@
-import { numberOfDigit, numberOfDigitsUsingLog } from '../NumberOfDigits'
+import { numberOfDigits } from '../NumberOfDigits.js'
 
-describe('NumberOfDigits', () => {
-  it('should return the correct number of digits for an integer', () => {
-    expect(numberOfDigit(1234000)).toBe(7)
+describe('numberOfDigits', () => {
+  test('numberOfDigits(0) returns 1', () => {
+    expect(numberOfDigits(0)).toBe(1)
   })
 
-  it('should return the correct number of digits for a negative number', () => {
-    expect(numberOfDigit(-2346243)).toBe(7)
+  test('numberOfDigits(1) returns 1', () => {
+    expect(numberOfDigits(1)).toBe(1)
   })
 
-  it.each([
-    [0, 1],
-    [123423232, 9],
-    [-123423232, 9],
-    [9999, 4]
-  ])(
-    'should return the correct number of digits in an integer',
-    (value, expected) => {
-      expect(numberOfDigitsUsingLog(value)).toBe(expected)
-    }
-  )
+  test('numberOfDigits(123) returns 3', () => {
+    expect(numberOfDigits(123)).toBe(3)
+  })
+
+  test('numberOfDigits(9999) returns 4', () => {
+    expect(numberOfDigits(9999)).toBe(4)
+  })
+
+  test('numberOfDigits(-9999) returns 4', () => {
+    expect(numberOfDigits(-9999)).toBe(4)
+  })
+
+  test('numberOfDigits(1000000) returns 7', () => {
+    expect(numberOfDigits(1000000)).toBe(7)
+  })
+
+  test('numberOfDigits(-1) returns 1', () => {
+    expect(numberOfDigits(-1)).toBe(1)
+  })
+
+  test('throws TypeError for float input', () => {
+    expect(() => numberOfDigits(1.5)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for string input', () => {
+    expect(() => numberOfDigits('123')).toThrow(TypeError)
+  })
+
+  test('throws TypeError for NaN', () => {
+    expect(() => numberOfDigits(NaN)).toThrow(TypeError)
+  })
 })