Create a humanized age string from a Javascript Date instance

gistfile1.js

Date.prototype.AGE_TABLE = [
  [         60, 'second'  , 'seconds' ],
  [       3600, 'minute'  , 'minutes' ],
  [      86400, 'hour'    , 'hours'   ],
  [     604800, 'day'     , 'days'    ],
  [    2628030, 'week'    , 'weeks'   ],
  [   31557600, 'month'   , 'months'  ],
  [ 4294967295, 'year'    , 'years'   ]
];

Date.prototype.age = function() {
  // determine age in seconds
  var seconds = (new Date() - this) / 1000.0;

  // future time?
  var future  = seconds < 0;

  // convert to absolute
  seconds = Math.abs(seconds);

  // walk through age table
  var suffix  = '';
  var divider = 1;
  for (var i = 0; i < this.AGE_TABLE.length; i++)
  {
    var secs      = this.AGE_TABLE[i][0];
    var singular  = this.AGE_TABLE[i][1];
    var plural    = this.AGE_TABLE[i][2];

    if (seconds < secs)
    {
      seconds /= divider;
      suffix  = (parseInt(seconds) > 1) ? plural : singular;
      break;
    }
    divider = secs;
  };

  return (future ? 'in ' : '') + 'about ' + parseInt(seconds) + ' ' + suff
};