code: function () {
        for (var url in resources) {
          if (pendingRequests[url])
            continue;
  
          Live.getHead(url, function (url, newInfo) {
            var oldInfo = resources[url],
                hasChanged = false;
            resources[url] = newInfo;
            for (var header in oldInfo) {
              // do verification based on the header type
              var oldValue = oldInfo[header],
                  newValue = newInfo[header],
                  contentType = newInfo["Content-Type"];
              switch (header.toLowerCase()) {
                case "etag":
                  if (!newValue) break;
                  // fall through to default
                default:
                  hasChanged = oldValue != newValue;
                  break;
              }
              // if changed, act
              if (hasChanged) {
                Live.refreshResource(url, contentType);
                break;
              }
            }
          });
        }
      }
docs: check all tracking resources for changes