Add helper toPercentage

Returns strings with percentage sign appended.

changelog.md

@@ -16,11 +16,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.1.0] - 2019-04-24
+
+### Added
+
+- Implement helper `toPercentage` to return strings with percentage sign appended.
+
 ## [1.0.0] - 2019-04-24
 
 ### Added
 
 - Calculate percentage difference between two numbers.
 
-[unreleased]: https://github.com/rodrigobdz/percentage-diff/compare/v1.0.0...HEAD
+[unreleased]: https://github.com/rodrigobdz/percentage-diff/compare/v1.1.0...HEAD
+[1.1.0]: https://github.com/rodrigobdz/percentage-diff/compare/v1.0.0...v1.1.0
 [1.0.0]: https://github.com/rodrigobdz/percentage-diff/compare/839407f777811173c2bbb62af850e3fc6ee07ebf...v1.0.0

index.js

@@ -1,6 +1,10 @@
 'use strict';
 
-module.exports = (firstNr, secondNr) => {
+function toPercentage(val) {
+	return `${val}%`;
+}
+
+function percentageDiff(firstNr, secondNr) {
 	if (typeof firstNr !== 'number') {
 		throw new TypeError(`Expected a number, got ${typeof firstNr}`);
 	}
@@ -12,4 +16,7 @@ module.exports = (firstNr, secondNr) => {
 	const percentageDiff = (secondNr - firstNr) / firstNr * 100;
 
 	return Number(percentageDiff.toFixed(2));
-};
+}
+
+module.exports = percentageDiff;
+module.exports.toPercentage = toPercentage;

readme.md

@@ -14,9 +14,11 @@ $ npm install percentage-diff
 const percentageDiff = require('percentage-diff');
 
 percentageDiff(50, 75);
+//=> 50
+percentageDiff.toPercentage(50);
 //=> 50%
 percentageDiff(45,35);
-//=> -22.22%
+//=> -22.22
 ```
 
 ## API
@@ -31,6 +33,12 @@ Type: `number`
 
 Type: `number`
 
+### percentageDiff.toPercentage(value)
+
+#### value
+
+Type: `number`
+
 ## Credits
 
 * [generator-lnm](https://github.com/rodrigobdz/generator-lnm) - Awesome node module generator

test.js

@@ -34,3 +34,7 @@ test('Handles zero division', t => {
 	t.is(percentageDiff(0, 0), NaN);
 	t.is(percentageDiff(0, 2), Infinity);
 });
+
+test('Format as percentage', t => {
+	t.is(percentageDiff.toPercentage(50), '50%');
+});