CodeWars: Human readable duration format Solution

Readability rather than trying to be clever

Approach

Convert to years, days, hours, minutes, and seconds

Join by , and use regex to replace the last occurence

Implementation

1function formatDuration(seconds) {
2  if (seconds === 0) return "now"
3
4  const addPlural = (number, noun) =>
5    number === 0 ? "" : `${number} ${noun}${number === 1 ? "" : "s"}`
6
7  const SECOND = 1
8  const MINUTE = SECOND * 60
9  const HOUR = MINUTE * 60
10  const DAY = HOUR * 24
11  const YEAR = DAY * 365
12
13  const years = Math.floor(seconds / YEAR)
14  seconds %= YEAR
15  const days = Math.floor(seconds / DAY)
16  seconds %= DAY
17  const hours = Math.floor(seconds / HOUR)
18  seconds %= HOUR
19  const minutes = Math.floor(seconds / MINUTE)
20  seconds %= MINUTE
21
22  return [
23    [years, "year"],
24    [days, "day"],
25    [hours, "hour"],
26    [minutes, "minute"],
27    [seconds, "second"],
28  ]
29    .map(([number, noun]) => addPlural(number, noun))
30    .filter(Boolean)
31    .join(", ")
32    .replace(/,\s([^,]+)$/, " and $1")
33}