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}