Returns a message describing the time of day given a start and end hour. A small and humble chunk of code, but I thought my approach was kind of nifty.

get-time-of-day.js

function getTimeOfDay (start, end) {
  if (start < 12 && end > 16) { return null } // not specific enough

  // we don't care about the window from 22:00 - 06:00
  const timesOfDay = Array(24)
    .fill('Morning', 6, 12)
    .fill('Afternoon', 12, 16)
    .fill('Evening', 16, 22)

  return Array.from(new Set(timesOfDay.slice(start, end)))
    .filter(value => !!value)
    .join(' / ')
}