feat(getOrdinalSuffix): Add getOrdinalSuffix functionality (#130)

Author: wsierakowski

src/get-ordinal-suffix.js

@@ -0,0 +1,23 @@
+export default getOrdinalSuffix
+
+/**
+ * Original source: https://stackoverflow.com/questions/13627308/add-st-nd-rd-and-th-ordinal-suffix-to-a-number
+ * Adds ordinal suffix (st, nd, rd and th) to a number
+ * @param {Number} num - number
+ * @return {String} String representation of the number with the ordinal suffix
+*/
+
+function getOrdinalSuffix(i) {
+  const j = i % 10
+  const k = i % 100
+  if (j === 1 && k !== 11) {
+    return `${i}st`
+  }
+  if (j === 2 && k !== 12) {
+    return `${i}nd`
+  }
+  if (j === 3 && k !== 13) {
+    return `${i}rd`
+  }
+  return `${i}th`
+}

src/index.js

@@ -45,6 +45,7 @@ import convertToRoman from './convertToRoman'
 import gcd from './gcd'
 import range from './range'
 import contains from './contains'
+import getOrdinalSuffix from './get-ordinal-suffix'
 
 export {
   isOdd,
@@ -94,4 +95,5 @@ export {
   gcd,
   range,
   contains,
+  getOrdinalSuffix,
 }

test/get-ordinal-suffix.test.js

@@ -0,0 +1,23 @@
+import test from 'ava'
+import {getOrdinalSuffix} from '../src'
+
+test('appends st, nd, th ordinal suffix to first 10 numbers', t => {
+  const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+  const expected = ['0th', '1st', '2nd', '3rd', '4th', '5th', '6th', '7th', '8th', '9th']
+  const actual = numbers.map(n => getOrdinalSuffix(n))
+  t.deepEqual(actual, expected)
+})
+
+test('appends th ordinal suffix to second 10 numbers', t => {
+  const numbers = [10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
+  const expected = ['10th', '11th', '12th', '13th', '14th', '15th', '16th', '17th', '18th', '19th']
+  const actual = numbers.map(n => getOrdinalSuffix(n))
+  t.deepEqual(actual, expected)
+})
+
+test('appends st, nd, th ordinal suffix to third 10 numbers', t => {
+  const numbers = [20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
+  const expected = ['20th', '21st', '22nd', '23rd', '24th', '25th', '26th', '27th', '28th', '29th']
+  const actual = numbers.map(n => getOrdinalSuffix(n))
+  t.deepEqual(actual, expected)
+})