format seconds with given formatter

formatTime.js

function formatTime(seconds, format) {
  var values = {
    h: Math.floor(seconds / 3600),
    m: Math.floor(seconds % 3600 / 60),
    s: Math.round(seconds % 60),
  }

  var type
  var value
  return format.split(':')
    .map(formatter => {
      type = formatter[0]
      value = values[type] + ''
      value = value.padStart(formatter.length - value.length, '0')
      return value
    })
    .join(':')
}