Add script to check images and show slide count

slides/README.md

@@ -45,3 +45,12 @@ and publish them to http://container.training/.
 Pull requests are automatically deployed to testing
 subdomains. I had no idea that I would ever say this
 about a static page hosting service, but it is seriously awesome. ⚡️💥
+
+
+## Extra bells and whistles
+
+You can run `./slidechecker foo.yml.html` to check for
+missing images and show the number of slides in that deck.
+It requires `phantomjs` to be installed. It takes some
+time to run so it is not yet integrated with the publishing
+pipeline.

slides/slidechecker.js

@@ -0,0 +1,21 @@
+#!/usr/bin/env phantomjs
+var system = require('system');
+var filename = system.args[1];
+var url = 'file://' + system.env.PWD + '/' + filename;
+
+var page = require('webpage').create();
+
+page.onResourceError = function(resourceError) {
+  console.log('ResourceError: ' + resourceError.url);
+}
+
+console.log('Loading: ' + url);
+page.open(url, function(status) {
+  console.log('Loaded: ' + url + '(' + status + ')');
+  var slides = page.evaluate(function() {
+    return document.getElementsByClassName('remark-slide-container');
+  });
+  console.log('Number of slides: ' + slides.length);
+  console.log('Done: ' + url + '(' + status + ')');
+  phantom.exit();
+});