support for custom slide number formatting #965

README.md

@@ -572,7 +572,16 @@ By default, Reveal is configured with [highlight.js](http://softwaremaniacs.org/
 If you would like to display the page number of the current slide you can do so using the ```slideNumber``` configuration value.
 
 ```javascript
+// Shows the slide number using default formatting
 Reveal.configure({ slideNumber: true });
+
+// Slide number formatting can be configured using these variables:
+//  h: current slide's horizontal index
+//  v: current slide's vertical index
+//  c: current slide index (flattened)
+//  t: total number of slides (flattened)
+Reveal.configure({ slideNumber: 'c / t' });
+
 ```