JS Tips #1: Human Readable Time

I have decided to continue writing my solutions to CodeWars puzzles in JavaScript and TypeScript. My goal is to continue practicing and not be satisfied with my current knowledge. So I am starting this “column” of tips on JavaScript and TypeScript. And I am starting today with the first problem: given a number, how can I transform it into a human-readable time?

The Problem: Human Readable Time

link to the kata

Write a function, which takes a non-negative integer (seconds) as input and returns the time in a human-readable format (HH:MM:SS)

HH = hours, padded to 2 digits, range: 00 - 99 MM = minutes, padded to 2 digits, range: 00 - 59 SS = seconds, padded to 2 digits, range: 00 - 59

The maximum time never exceeds 359999 (99:59:59)

My Solution

The problem is rated 5 kyu. It is a wrong rating: it is easier. The most complicated part is counting the number of seconds in a minute and in an hour. Spoiler: there are always 60 seconds in a minute, and 3600 seconds in an hour.

Knowing this, I can use the Remainder Operator (%) to get the values I need:

const getSeconds = (s: number): number => s % 60;
const getMinutes = (s: number): number => Math.floor((s % 3600) / 60);
const getHours = (s: number): number => Math.floor(s / 3600);

The second difficulty is understanding how to convert numbers into a string. Or, more precisely, how to make sure that one-digit numbers are preceded by a zero. To do this, I can use the String.padStart() method, setting the length to 2 and using the 0 character as the padString.

const pad = (n: number): string => n.toString().padStart(2, "0");

Finally, I can use the Template Literals to create the final string.

`${pad(hh)}:${pad(mm)}:${pad(ss)}`;

By putting all these functions together, I get the solution to my programming problem.

const getSeconds = (s: number): number => s % 60;
const getMinutes = (s: number): number => Math.floor((s % 3600) / 60);
const getHours = (s: number): number => Math.floor(s / 3600);

const pad = (n: number): string => n.toString().padStart(2, "0");

export function humanReadable(seconds: number): string {
  const s: number = getSeconds(seconds);
  const m: number = getMinutes(seconds);
  const h: number = getHours(seconds);

  return `${pad(h)}:${pad(m)}:${pad(s)}`;
}