Add REVEAL_EXTRA_SCRIPT to add custom javascript code

If you want to add extra code outside of the =Reveal.initialize= block, then =#+REVEAL_EXTRA_SCRIPT= can be used. The code will be inserted after closing the =Reveal.initialize= statement, but before the closing =</script>= tag.

Readme.org

@@ -879,6 +879,11 @@ To disable the automatic TOC, add =toc:nil= to =#+OPTIONS=
  ~#+REVEAL_INIT_SCRIPT~ (multiple statements are concatenated) or by
    custom variable ~org-reveal-init-script~.
 
+   If you want to add extra code outside of the ~Reveal.initialize~
+   block, then ~#+REVEAL_EXTRA_SCRIPT~ can be used. The code will be
+   inserted after closing the ~Reveal.initialize~ statement, but before
+   the closing ~</script>~ tag.
+
 ** Executable Source Blocks
 To allow live execution of code in some languages, enable the klipse plugin by setting ~org-reveal-klipsify-src~ to non-nil.  Src blocks with the languages ~js~, ~clojure~, ~html~, ~python~, ~ruby~, ~scheme~, ~php~ will be executed with output shown in a console-like environment.  See the source code of ~org-reveal-src-block~ for more details.  
 

ox-reveal.el

@@ -100,6 +100,7 @@
     (:reveal-default-frag-style "REVEAL_DEFAULT_FRAG_STYLE" nil org-reveal-default-frag-style t)
     (:reveal-single-file nil "reveal_single_file" org-reveal-single-file t)
     (:reveal-init-script "REVEAL_INIT_SCRIPT" nil org-reveal-init-script space)
+    (:reveal-extra-script "REVEAL_EXTRA_SCRIPT" nil org-reveal-extra-script space)
     (:reveal-init-options "REVEAL_INIT_OPTIONS" nil org-reveal-init-options newline)
     (:reveal-highlight-css "REVEAL_HIGHLIGHT_CSS" nil org-reveal-highlight-css nil)
     (:reveal-reveal-js-version "REVEAL_REVEAL_JS_VERSION" nil nil t)
@@ -302,6 +303,11 @@ BEFORE the plugins that depend on them."
   :group 'org-export-reveal
   :type 'string)
 
+(defcustom org-reveal-extra-script nil
+  "Custom script that will be passed added to the script block, after Reveal.initialize."
+  :group 'org-export-reveal
+  :type 'string)
+
 (defcustom org-reveal-highlight-css "%r/lib/css/zenburn.css"
   "Highlight.js CSS file."
   :group 'org-export-reveal
@@ -802,7 +808,11 @@ dependencies: [
          ))
         (let ((init-script (plist-get info :reveal-init-script)))
           (if init-script (concat (if in-single-file "" ",") init-script)))
-     "});\n</script>\n")))
+        "});\n"
+        (let ((extra-script (plist-get info :reveal-extra-script)))
+          (if extra-script extra-script))
+     "
+\n</script>\n")))
 
 (defun org-reveal-plugin-scripts-4 (info)
   "Return scripts for initializing reveal.js 4.x builtin scripts"