Improve Mean method

Maths/AverageMean.js

@@ -1,29 +1,23 @@
-'use strict'
-/*
-    author: PatOnTheBack
-    license: GPL-3.0 or later
-
-    Modified from:
-        https://github.com/TheAlgorithms/Python/blob/master/maths/average.py
-
-    This script will find the average (mean) of an array of numbers.
-
-    More about mean:
-        https://en.wikipedia.org/wiki/Mean
-*/
+/**
+ * @function mean
+ * @description This script will find the mean value of a array of numbers.
+ * @param {Integer[]} nums - Array of integer
+ * @return {Integer} - mean of nums.
+ * @see [Mean](hhttps://en.wikipedia.org/wiki/Mean)
+ * @example mean([1, 2, 4, 5]) = 3
+ * @example mean([10, 40, 100, 20]) = 42.5
+ */
 
 const mean = (nums) => {
-  // This is a function returns average/mean of array
-  let sum = 0
+  if (!Array.isArray(nums)) {
+    throw new TypeError('Invalid Input')
+  }
 
   // This loop sums all values in the 'nums' array using forEach loop
-  nums.forEach(function (current) {
-    sum += current
-  })
+  const sum = nums.reduce((sum, cur) => sum + cur, 0)
 
   // Divide sum by the length of the 'nums' array.
-  const avg = sum / nums.length
-  return avg
+  return sum / nums.length
 }
 
 export { mean }

Maths/test/AverageMean.test.js

@@ -4,8 +4,18 @@ describe('Tests for average mean', () => {
   it('should be a function', () => {
     expect(typeof mean).toEqual('function')
   })
+
+  it('should throw error for invalid input', () => {
+    expect(() => mean(123)).toThrow()
+  })
+
   it('should return the mean of an array of numbers', () => {
     const meanFunction = mean([1, 2, 4, 5])
     expect(meanFunction).toBe(3)
   })
+
+  it('should return the mean of an array of numbers', () => {
+    const meanFunction = mean([10, 40, 100, 20])
+    expect(meanFunction).toBe(42.5)
+  })
 })