to_relative_date.jquer.js

/*
 * The MIT License
 * 
 * Copyright (c) 2009 James F. Herdman
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *   THE SOFTWARE.
 */
(function($) {
  $.fn.toRelativeDate = function() {
    function relativeTimeAgo(pastDate) {
      var delta       = new Date() - pastDate;
      var units       = null;
      var conversions = {
        millisecond: 1, // ms    -> ms
        second: 1000,   // ms    -> sec
        minute: 60,     // sec   -> min
        hour:   60,     // min   -> hour
        day:    24,     // hour  -> day
        month:  30,     // day   -> month (roughly)
        year:   12      // month -> year
      }

      for(var key in conversions) {
        if(delta < conversions[key]) {
          break;
        } else {
          units = key; // keeps track of the selected key over the iteration
          delta = delta / conversions[key];
        }
      }

      // pluralize a unit when the difference is greater than 1.
      delta = Math.floor(delta);
      if(delta != 1) units += "s";
      return [delta, units, "ago"].join(" ");
    }

    this.each(function() {
      var elem  = $(this);
      var stamp = new Date(Date.parse(elem.html()));
      elem.text(relativeTimeAgo(stamp));
    });
  }
})(jQuery);