"merge with master branch (release 0.4.1)"

js/impress.js

@@ -140,7 +140,6 @@
     if (!impressSupported) {
         // we can't be sure that `classList` is supported
         body.className += " impress-not-supported ";
-        return;
     } else {
         body.classList.remove("impress-not-supported");
         body.classList.add("impress-supported");
@@ -170,7 +169,11 @@
     };
     
     var impress = window.impress = function ( rootId ) {
-
+        
+        if (!impressSupported) {
+            return null;
+        }
+        
         rootId = rootId || "impress";
         
         // if already initialized just return the API
@@ -471,6 +474,9 @@
         });
 
     };
+    
+    impress.supported = impressSupported;
+    
 })(document, window);
 
 // EVENTS
@@ -480,6 +486,11 @@
     
     var impress = window.impress;
     
+    // if impress is not supported don't add any handlers
+    if (!impress.supported) {
+        return;
+    }
+    
     // throttling function calls, by Remy Sharp
     // http://remysharp.com/2010/07/21/throttling-function-calls/
     var throttle = function (fn, delay) {