TheAlgorithms · appgurueu · Oct 27, 2022 · Oct 26, 2022 · Oct 26, 2022 · Oct 27, 2022
@@ -9,6 +9,14 @@
  */
 
 const factorial = (n) => {
+  if (!(typeof n === 'number')) {
+    throw new TypeError('Not a Number')
+  }
+
+  if ((n % 1) !== 0) {
+    throw new RangeError('Not a Whole Number')
+  }
+
   if (n === 0) {
     return 1
   }

@@ -8,4 +8,11 @@ describe('Factorial', () => {
   it('should return factorial 120 for value "5"', () => {
     expect(factorial(5)).toBe(120)
   })
+
+  it('Throw Error for Invalid Input', () => {
+    expect(() => factorial('-')).toThrow('Not a Number')
+    expect(() => factorial(null)).toThrow('Not a Number')
+    expect(() => factorial(undefined)).toThrow('Not a Number')
+    expect(() => factorial(3.142)).toThrow('Not a Whole Number')
+  })
 })