source: Dev/trunk/node_modules/mocha/lib/ms.js

/**
 * Helpers.
 */

var s = 1000;
var m = s * 60;
var h = m * 60;
var d = h * 24;
var y = d * 365.25;

/**
 * Parse or format the given `val`.
 *
 * Options:
 *
 *  - `long` verbose formatting [false]
 *
 * @param {String|Number} val
 * @param {Object} options
 * @return {String|Number}
 * @api public
 */

module.exports = function(val, options){
  options = options || {};
  if ('string' == typeof val) return parse(val);
  return options.long
    ? long(val)
    : short(val);
};

/**
 * Parse the given `str` and return milliseconds.
 *
 * @param {String} str
 * @return {Number}
 * @api private
 */

function parse(str) {
  var match = /^((?:\d+)?\.?\d+) *(ms|seconds?|s|minutes?|m|hours?|h|days?|d|years?|y)?$/i.exec(str);
  if (!match) return;
  var n = parseFloat(match[1]);
  var type = (match[2] || 'ms').toLowerCase();
  switch (type) {
    case 'years':
    case 'year':
    case 'y':
      return n * y;
    case 'days':
    case 'day':
    case 'd':
      return n * d;
    case 'hours':
    case 'hour':
    case 'h':
      return n * h;
    case 'minutes':
    case 'minute':
    case 'm':
      return n * m;
    case 'seconds':
    case 'second':
    case 's':
      return n * s;
    case 'ms':
      return n;
  }
}

/**
 * Short format for `ms`.
 *
 * @param {Number} ms
 * @return {String}
 * @api private
 */

function short(ms) {
  if (ms >= d) return Math.round(ms / d) + 'd';
  if (ms >= h) return Math.round(ms / h) + 'h';
  if (ms >= m) return Math.round(ms / m) + 'm';
  if (ms >= s) return Math.round(ms / s) + 's';
  return ms + 'ms';
}

/**
 * Long format for `ms`.
 *
 * @param {Number} ms
 * @return {String}
 * @api private
 */

function long(ms) {
  return plural(ms, d, 'day')
    || plural(ms, h, 'hour')
    || plural(ms, m, 'minute')
    || plural(ms, s, 'second')
    || ms + ' ms';
}

/**
 * Pluralization helper.
 */

function plural(ms, n, name) {
  if (ms < n) return;
  if (ms < n * 1.5) return Math.floor(ms / n) + ' ' + name;
  return Math.ceil(ms / n) + ' ' + name + 's';
}