formatDuration.js

formatDuration.js

const LABELS = ['year', 'day', 'hour', 'minute', 'second'];

function formatDuration (seconds) {
  if (seconds === 0) return 'now';
  
  let minutes = seconds / 60 >> 0;
  let hours = minutes > 59 ? minutes / 60 >> 0 : 0;
  let days = hours > 23 ? hours / 24 >> 0 : 0;
  const years = days > 364 ? days / 365 >> 0 : 0
  
  if (seconds > 59) seconds = seconds % 60;
  if (minutes > 59) minutes = minutes % 60;
  if (hours > 23) hours = hours % 24;
  if (days > 364) days = days % 365;
  
  return [years, days, hours, minutes, seconds]
    .map((item, idx) => item && (item > 1 ? item + ' ' + LABELS[idx] + 's' : item + ' ' + LABELS[idx]))
    .filter(item => item) // filter out zeroes
    .join(', ')
    .replace(/(^.+)([,])(.+$)/, '$1 and$3') // replace the "something, something" part at the end
}

const Test = {
  assertEquals(a, b) {
    if (a !== b) throw new Error(`Expected: ${b} but instead got: ${a}`);
    console.log(`Test passed: ${b}`);
  }
};

Test.assertEquals(formatDuration(1), "1 second");
Test.assertEquals(formatDuration(62), "1 minute and 2 seconds");
Test.assertEquals(formatDuration(120), "2 minutes");
Test.assertEquals(formatDuration(3600), "1 hour");
Test.assertEquals(formatDuration(3662), "1 hour, 1 minute and 2 seconds");