feat(tail): add tail function (#177)

Add tail function that returns all but the first element of array.
* Return [] for null and undefined

Closes #176

Author: jzabala

src/index.js

@@ -63,6 +63,7 @@ import getQueryStringValue from './get-query-string-value'
 import isLeapYear from './leap-year'
 import removeElementFromArray from './removeElementFromArray'
 import generatePassword from './generate-password'
+import tail from './tail'
 
 export {
   reverseArrayInPlace,
@@ -130,4 +131,5 @@ export {
   isLeapYear,
   removeElementFromArray,
   generatePassword,
+  tail,
 }

src/tail.js

@@ -0,0 +1,13 @@
+export default tail
+
+/**
+ * Original Source: https://stackoverflow.com/a/35361274/5801753
+ *
+ * This function gets all but the first element of array
+ *
+ * @param {Array} array - The array to get the tail from
+ * @return {Array} - The array without the first element
+ */
+function tail(array) {
+  return Boolean(array) ? array.slice(1) : []
+}

test/tail.test.js

@@ -0,0 +1,27 @@
+import test from 'ava'
+import {tail} from '../src'
+
+test('returns empty array for null', t => {
+  const expected = []
+  const actual = tail(null)
+  t.deepEqual(actual, expected)
+})
+
+test('returns empty array for undefined', t => {
+  const expected = []
+  const actual = tail(undefined)
+  t.deepEqual(actual, expected)
+})
+
+test('returns empty array for empty array', t => {
+  const expected = []
+  const actual = tail([])
+  t.deepEqual(actual, expected)
+})
+
+test('returns the tail of array', t => {
+  const original = [1, 2, 3, 4, 5]
+  const expected = [2, 3, 4, 5]
+  const actual = tail(original)
+  t.deepEqual(actual, expected)
+})