Script.js

(function() {
  "use strict";

  
  // This following code is taken from
  // https://github.com/thieman/github-selfies/blob/master/chrome/selfie.js
  var allowedPaths = [
    /github.com\/[\w\-]+\/[\w\-]+\/pull\/\d+/
  ];

  // Inject the code from fn into the page, in an IIFE.
  function inject(fn) {
    var script = document.createElement('script');
    var parent = document.documentElement;
    script.textContent = '('+ fn +')();';
    parent.appendChild(script);
    parent.removeChild(script);
  }

  // Post a message whenever history.pushState is called. GitHub uses
  // pushState to implement page transitions without full page loads.
  // This needs to be injected because content scripts run in a sandbox.
  inject(function() {
    var pushState = history.pushState;
    history.pushState = function on_pushState() {
      window.postMessage('extension:pageUpdated', '*');
      return pushState.apply(this, arguments);
    };
    var replaceState = history.replaceState;
    history.replaceState = function on_replaceState() {
      window.postMessage('extension:pageUpdated', '*');
      return replaceState.apply(this, arguments);
    };
  });

  // Do something when the extension is loaded into the page,
  // and whenever we push/pop new pages.
  window.addEventListener("message", function(event) {
    if (event.data === 'extension:pageUpdated') {
      load();
    }
  });

  window.addEventListener("popstate", load);
  load();

  // End of code from https://github.com/thieman/github-selfies/blob/master/chrome/selfie.js

  function load() {
    chrome.runtime.sendMessage({action: 'load'}, function(response) {
      initialize();

      var observer = new MutationObserver(function (mutations) {

        mutations.forEach(function (mutation) {
          var fileActionDiv = mutation.target.querySelector(".file-actions");
          if (fileActionDiv != null) {
            initialize();
            return;
          }
        });
      });
      var config = {
        childList: true,
        characterData: true,
        subtree: true
      };

      // pass in the target node, as well as the observer options
      var files = document.querySelector('#files');
      if (files != null) {
        observer.observe(files, config);
      }
    });
  }

  function any(array, predicate) {
    for (var i = 0; i < array.length; i++) {
      if (predicate(array[i])) {
        return true;
      }
    }
    return false;
  }
})();