feat(isArray): Add isArray and tests #38 (#39)

Added a method `isArray` to check if an object passed as a parameter is
a javascript array.

Includes 6 tests and 100% coverage.

Author: rheaditi

src/index.js

@@ -7,7 +7,7 @@ import arrayFill from './array-fill'
 import sortObjectsArray from './sort-objects-array'
 import objectValuesToString from './object-values-to-string'
 import getObjectSize from './get-object-size'
-
+import isArray from './is-array'
 
 export {
   flatten,
@@ -19,4 +19,5 @@ export {
   sortObjectsArray,
   objectValuesToString,
   getObjectSize,
+  isArray,
 }

src/is-array.js

@@ -0,0 +1,16 @@
+export default isArray
+
+/**
+ * Original Source: http://stackoverflow.com/a/4775737
+ *
+ * This method checks whether an object passed as an
+ * argument is a javascript Array or not.
+ *
+ * @param {Object} someObject - the object to check
+ * @return {Boolean} - True if someObject is an array else false
+ */
+
+function isArray(someObject) {
+  const objectToString = Object.prototype.toString.call(someObject)
+  return objectToString === '[object Array]'
+}

test/is-array.js

@@ -0,0 +1,44 @@
+import test from 'ava'
+import {isArray} from '../src'
+
+test('check an actual array of strings', t => {
+  const object = ['one','two','three']
+  const expected = true
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})
+
+test('check a nested array', t => {
+  const object = ['one',[2,3,4],'three']
+  const expected = true
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})
+
+test('check a strings', t => {
+  const object = 'hello world'
+  const expected = false
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})
+
+test('check a JSON object', t => {
+  const object = { keyOne: 'value1', keyTwo: 'value2'}
+  const expected = false
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})
+
+test('check null', t => {
+  const object = null
+  const expected = false
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})
+
+test('check undefined', t => {
+  const object = undefined
+  const expected = false
+  const actual = isArray(object)
+  t.deepEqual(actual, expected)
+})