// ==UserScript==
// @name         Facebook real time time
// @match        https://www.facebook.com/*
// @grant        none
// ==/UserScript==

function update_timestamps () {
    function pretty_time (time) {
      hours = Math.floor(time / 3600)
      minutes = Math.floor(time / 60) - hours * 60;
      seconds = time % 60;
      function pad (n) {return ('0' + n).substr(-2)};
      pretty = pad(hours) + ':' + pad(minutes) + ':' + pad(seconds);
      return pretty;
    }
    abbrs = document.getElementsByTagName('abbr');
    current = new Date().getTime() / 1000 | 0;
    for (i in abbrs) {
      try {
        abbrs[i].attributes['data-utime']
      } catch (e) {
        continue;
      }
      diff = current - parseInt(abbrs[i].attributes['data-utime'].value);
      if (diff < 3 * 60 * 60)
        abbrs[i].innerHTML = pretty_time(diff);
    }
    setTimeout(update_timestamps, 1000);
}
update_timestamps();