feat: add function to stringify numbers to time strings

Author: TimoBechtel

README.md

@@ -1,5 +1,5 @@
 <h1 align="center">@compactjs/parse-time</h1>
-<h3 align="center">Tiny time parser</h3>
+<h3 align="center">Tiny hour parser & stringifier</h3>
 <p align="center">
   <a href="https://www.npmjs.com/package/@compactjs/parse-time" target="_blank">
     <img alt="Version" src="https://img.shields.io/npm/v/@compactjs/parse-time.svg">
@@ -44,13 +44,30 @@ npm install @compactjs/parse-time
 ### As module:
 
 ```javascript
-import { parse } from '@compactjs/parse-time';
+import { parse, stringify } from '@compactjs/parse-time';
 ```
 
 ### Example:
 
 ```javascript
+// parse a time string to a number
 parse('13:30'); // => 13.5
+parse('13:19:48'); // => 13.33
+
+// stringify a number to a time string
+stringify(13.33); // => 13:19:48
+
+// formating options:
+stringify(13.33, 'hh'); // => 13
+stringify(13.33, 'hh:mm'); // => 13:19
+stringify(13.33, 'hh:mm:ss'); // => 13:19:48
+
+// it accepts numbers higher than 24
+stringify(34.5); // => 34:30:00
+
+// to limit to a range between 0 and 24 (or 0-12),
+// I recommend to use https://github.com/CompactJS/limit
+stringify(limit(34.5, 24)); // => 10:30:00
 ```
 
 ## Run tests

src/index.ts

@@ -9,3 +9,32 @@ export function parse(timeString: string): number {
     .split(':')
     .reduce((hours, hour, i) => hours + parseInt(hour) / Math.pow(60, i), 0);
 }
+
+type TimeUnit = 'hh' | 'mm' | 'ss';
+type TimeFormat =
+  | `${TimeUnit}`
+  | `${TimeUnit}:${TimeUnit}`
+  | `${TimeUnit}:${TimeUnit}:${TimeUnit}`;
+
+/**
+ * Converts hours as float to a string representation, separated by colon
+ * @param hours time as float
+ * @returns Time as string Format: 'hh:mm[:ss]'
+ * @example stringify(11.5) // => '11:30'
+ */
+export function stringify(
+  hours: number,
+  format: TimeFormat = 'hh:mm:ss'
+): string {
+  const hoursString = pad(Math.floor(hours));
+  const minutesString = pad(Math.floor(hours * 60) % 60);
+  const secondsString = pad(Math.floor(hours * 3600) % 60);
+  return format
+    .replace(/hh/g, hoursString)
+    .replace(/mm/g, minutesString)
+    .replace(/ss/g, secondsString);
+}
+
+function pad(number: string | number): string {
+  return `${number}`.length === 1 ? `0${number}` : `${number}`;
+}

test/index.test.js

@@ -1,31 +1,5 @@
-const assert = require('assert');
-const { parse } = require('..');
+const testParseFunction = require('./parse.test');
+const testStringifyFunction = require('./stringify.test');
 
-console.log('Testing:');
-
-const test = (example) => {
-  const log = (example, expected) =>
-    console.log(`\u001B[32m✓\u001B[39m ${example} = ${expected}`);
-  return {
-    isNaN() {
-      assert(isNaN(example));
-      log(example, 'NaN');
-    },
-    equals(expected) {
-      assert.equal(parse(example), expected);
-      log(example, expected);
-    },
-  };
-};
-
-test('00:00').equals(0);
-test('12:30').equals(12.5);
-test('24:00').equals(24);
-test('02:14').equals(2 + 14 / 60);
-test('60:366').equals(66.1);
-test('13:30:30').equals(13 + 0.5 + 0.5 / 60);
-test('1:1').equals(1 + 1 / 60);
-test('hello:world').isNaN();
-test('helloworld').isNaN();
-test(':30').isNaN();
-test('60:60:60:60').equals(61 + 60 / 60 / 60 + 60 / 60 / 60 / 60);
+testParseFunction();
+testStringifyFunction();

test/parse.test.js

@@ -0,0 +1,32 @@
+const assert = require('assert');
+const { parse } = require('..');
+
+const test = (example) => {
+  const log = (example, expected) =>
+    console.log(`\u001B[32m✓\u001B[39m ${example} = ${expected}`);
+  return {
+    isNaN() {
+      assert(isNaN(parse(example)));
+      log(example, 'NaN');
+    },
+    equals(expected) {
+      assert.equal(parse(example), expected);
+      log(example, expected);
+    },
+  };
+};
+
+module.exports = function () {
+  console.log('Testing, parse function.');
+  test('00:00').equals(0);
+  test('12:30').equals(12.5);
+  test('24:00').equals(24);
+  test('02:14').equals(2 + 14 / 60);
+  test('60:366').equals(66.1);
+  test('13:30:30').equals(13 + 0.5 + 0.5 / 60);
+  test('1:1').equals(1 + 1 / 60);
+  test('hello:world').isNaN();
+  test('helloworld').isNaN();
+  test(':30').isNaN();
+  test('60:60:60:60').equals(61 + 60 / 60 / 60 + 60 / 60 / 60 / 60);
+};

test/stringify.test.js

@@ -0,0 +1,34 @@
+const assert = require('assert');
+const { stringify } = require('..');
+
+const test = (example, format) => {
+  const log = (example, expected) =>
+    console.log(`\u001B[32m✓\u001B[39m ${example} = ${expected}`);
+  return {
+    isNaN() {
+      assert(isNaN(stringify(example)));
+      log(example, 'NaN');
+    },
+    equals(expected) {
+      assert.strictEqual(stringify(example, format), expected);
+      log(example, expected);
+    },
+  };
+};
+
+module.exports = function () {
+  console.log('Testing stringify function');
+  test(0, 'hh:mm').equals('00:00');
+  test(0, 'hh:mm:ss').equals('00:00:00');
+  test(1.5, 'hh:mm:ss').equals('01:30:00');
+  test(13.33, 'hh:mm:ss').equals('13:19:48');
+  test(13.33, 'mm:ss').equals('19:48');
+  // weird format, but it's a valid format
+  test(13.33, 'ss:hh:mm').equals('48:13:19');
+
+  // invalid input
+  test('23:43:39', 'hh:mm:ss').equals('NaN:NaN:NaN');
+
+  // more than 24 hours allowed
+  test(34.5).equals('34:30:00');
+};