1) Ditch caching in isEventSupported, to make example (and mechanis…

…m of this inference) easier to understand.

2) Change `isEventSupported` to use generic element (DIV), when supplied object doesn't implement `Node` interface (and so has no `setAttribute`).
Something like `isEventSupported('hashchange', window)` now internally tries `<DIV>.setAttribute('hashchange', '')`, since `window` is one of `setAttribute`-less objects.
This change fixes some of the false positives from previous verion.

3) Add few more HTML5, as well as proprietary "pageshow" and "pagehide" events to test page.

isEventSupported.js

@@ -19,6 +19,45 @@
  */
 var isEventSupported = (function(){
 
+  var TAGNAMES = {
+    'select':'input','change':'input',
+    'submit':'form','reset':'form',
+    'error':'img','load':'img','abort':'img'
+  }
+
+  function isEventSupported(eventName, element) {
+
+    element = element || document.createElement(TAGNAMES[eventName] || 'div');
+    eventName = 'on' + eventName;
+
+    // When using `setAttribute`, IE skips "unload", WebKit skips "unload" and "resize", whereas `in` "catches" those
+    var isSupported = (eventName in element);
+
+    if (!isSupported) {
+      // if it has no `setAttribute` (i.e. doesn't implement Node interface), try generic element
+      if (!element.setAttribute) {
+        element = document.createElement('div');
+      }
+      if (element.setAttribute && element.removeAttribute) {
+        element.setAttribute(eventName, '');
+        isSupported = typeof element[eventName] == 'function';
+
+        // if property was created, "remove it" (by setting value to `undefined`)
+        if (typeof element[eventName] != 'undefined') {
+          element[eventName] = void 0;
+        }
+        element.removeAttribute(eventName);
+      }
+    }
+
+    element = null;
+    return isSupported;
+  }
+  return isEventSupported;
+})();
+
+var isEventSupportedWithCache = (function(){
+
   var TAGNAMES = {
     'select':'input','change':'input',
     'submit':'form','reset':'form',
@@ -40,15 +79,21 @@ var isEventSupported = (function(){
     // When using `setAttribute`, IE skips "unload", WebKit skips "unload" and "resize", whereas `in` "catches" those
     var isSupported = (eventName in element);
 
-    if (!isSupported && element.setAttribute && element.removeAttribute) {
-      element.setAttribute(eventName, 'return;');
-      isSupported = typeof element[eventName] == 'function';
-
-      // if property was created, "remove it" (by setting value to `undefined`)
-      if (typeof element[eventName] != 'undefined') {
-        element[eventName] = void 0;
+    if (!isSupported) {
+      // if it has no `setAttribute` (i.e. doesn't implement Node interface), try generic element
+      if (!element.setAttribute) {
+        element = document.createElement('div');
+      }
+      if (element.setAttribute && element.removeAttribute) {
+        element.setAttribute(eventName, '');
+        isSupported = typeof element[eventName] == 'function';
+
+        // if property was created, "remove it" (by setting value to `undefined`)
+        if (typeof element[eventName] != 'undefined') {
+          element[eventName] = void 0;
+        }
+        element.removeAttribute(eventName);
       }
-      element.removeAttribute(eventName);
     }
 
     element = null;

test.js

@@ -27,13 +27,13 @@ w('keyup');
 document.write('<h2>HTML events</h2>');
 
 w('load');
-w('unload', typeof window.onunload != 'undefined' ? window : void 0 );
+w('unload', window);
 w('abort');
 w('error');
 
 document.write('<h2>View events</h2>');
 
-w('resize');
+w('resize', window);
 w('scroll');
 
 document.write('<h2>Form events:</h2>');
@@ -89,7 +89,7 @@ w('stop', document);
 w('readystatechange');
 w('beforeprint', document.body);
 w('afterprint', document.body);
-w('beforeunload', typeof window.onbeforeunload != 'undefined' ? window : void 0 );
+w('beforeunload', window);
 
 document.write('<h2>Unexistent (most likely) events:</h2>');
 
@@ -118,4 +118,17 @@ document.write('<h2>HTML5 events</h2>');
 w('hashchange', document.body);
 w('online', document.body);
 w('offline', document.body);
-w('message', typeof window.onmessage != 'undefined' ? window : void 0 );
+w('message', window);
+w('undo', document.body);
+w('redo', document.body);
+w('storage', window);
+w('popstate', window);
+
+w('canplay', document.createElement('video'));
+w('seeking', document.createElement('video'));
+w('seekend', document.createElement('video'));
+
+document.write('<h2>Proprietary</h2>');
+
+w('pageshow', window);
+w('pagehide', window);