feat(arrayAverage): implements a function that calculates the average of the values of an array (#131)

Author: mgs96

src/array-average.js

@@ -0,0 +1,15 @@
+export default average
+
+/**
+ * Original source: https://stackoverflow.com/a/29544442/4573129
+ * This method will return the average of an array
+ * @param {Array} array - the array to calculate average
+ * @return {Number} - the average of the values in the array
+ */
+ 
+function average(array) {
+  const sum = array.reduce((total, current) => {
+    return total + current
+  })
+  return sum / array.length
+}

src/index.js

@@ -46,6 +46,7 @@ import gcd from './gcd'
 import range from './range'
 import contains from './contains'
 import getOrdinalSuffix from './get-ordinal-suffix'
+import arrayAverage from './array-average'
 
 export {
   isOdd,
@@ -96,4 +97,5 @@ export {
   range,
   contains,
   getOrdinalSuffix,
+  arrayAverage,
 }

test/array-average.test.js

@@ -0,0 +1,9 @@
+import test from 'ava'
+import {arrayAverage} from '../src'
+
+test('Calculates the average of an array', t => {
+  const array = [1, 2, 3, 4]
+  const expected = 2.5
+  const actual = arrayAverage(array)
+  t.deepEqual(actual, expected)
+})