A general method which splits a metric expressed in a single smaller unit into multiple higher units

formatUnit.js

// A general method which splits a metric
// expressed in a single smaller unit into multiple
// higher units

// 1689 minutes => 1 day 9 hours 9 minutes
// 1678 millimeter => 1 meter 67 centimeter 8 millimeter

// The method takes two parameters, the metric itself
// and an array which defines the conversion

// Say, you want to convert x minutes to 
// a days b hours and c minutes
// the conversion array would take in 
// [1140, 60, 1]
// 1 day = 1440 minutes
// 1 hour = 60 minutes
// 1 minute = 1 minute

// Note: Array.shift() returns the first element of the 
// array and removes it in place

// arr = [1, 2]
// arr.shift() => 1
// arr => [2]

function formatUnit (metric, divisions) {
  var result = [];

  // a recursive function which repeatedly breaks
  // the metric into higher units until it can be
  // be expressed in the unit in which it was passed as
  function smasher(reducedMetric, division) {
    // if we have exhausted all the conversion rule
    // pass the result
    if (!divisions.length) {
      result.push(reducedMetric);
      return result;
    } else {
      // if the current metric is less than 
      // one unit of the current unit
      // (like 30 minutes < 1 hour)
      if (reducedMetric < division) {
        result.push(0);
        return smasher(reducedMetric, divisions.shift());
      } else {
        result.push(Math.floor(reducedMetric / division));
        return smasher(reducedMetric % division, divisions.shift());
      }
    }
  }

  return smasher(metric, divisions.shift());
}