Safari の人: https://dl.dropbox.com/u/248381/safari/github-pr-counter.safariextz

github-pr-counter.user.js

// ==UserScript==
// @name           GitHub PR counter
// @namespace      jp.riaf.github.pull-counter
// @description    GitHub pull request review counter
// @author         Keisuke SATO <[email protected]>
// @run-at         document-end
// @match          https://github.com/*/pull/*
// @version        1.0
// ==/UserScript==

(function (d, func) {
  var h = d.getElementsByTagName('head')[0];
  var s1 = d.createElement('script');

  s1.setAttribute('src', 'https://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js');
  s1.addEventListener('load', function() {
      var s2 = d.createElement('script');
      s2.textContent = 'jQuery.noConflict();(' + func.toString() + ')(jQuery);';
      h.appendChild(s2);
  }, false);
  h.appendChild(s1);

})(document, function($) {
  var count_positive = 0
    , count_negative = 0
    , $counter = $('<span />').addClass('pull-number')
    , counter_refresh = function() {
        $counter.text('+' + count_positive + ' / -' + count_negative);
      };

  $(function() {
    counter_refresh();
    $('.pull-head-meta').append($counter);

    $('.comment-content .comment-body').each(function(){
      var $self = $(this)
        , text = $self.text();

      // string
      count_positive += (text.match(/\+1/g) || []).length;
      count_negative += (text.match(/\-1/g) || []).length;

      // emoji
      count_positive += $('.emoji[title=":+1:"]', $self).length;
      count_negative += $('.emoji[title=":-1:"]', $self).length;

      counter_refresh();
    });
  });
});