crossBrowser_initKeyboardEvent.js

void function() {//closure

var global = this
  , _initKeyboardEvent_type = (function( e ) {
		try {
			e.initKeyboardEvent(
				"keyup" // in DOMString typeArg
				, false // in boolean canBubbleArg
				, false // in boolean cancelableArg
				, global // in views::AbstractView viewArg
				, "+" // [test]in DOMString keyIdentifierArg | webkit event.keyIdentifier | IE9 event.key
				, 3 // [test]in unsigned long keyLocationArg | webkit event.keyIdentifier | IE9 event.location
				, true // [test]in boolean ctrlKeyArg | webkit event.shiftKey | old webkit event.ctrlKey | IE9 event.modifiersList
				, false // [test]shift | alt
				, true // [test]shift | alt
				, false // meta
				, false // altGraphKey
			);
			
			
			
			/*
			// Safari and IE9 throw Error here due keyCode, charCode and which is readonly
			// Uncomment this code block if you need legacy properties
			delete e.keyCode;
			_Object_defineProperty(e, {writable: true, configurable: true, value: 9})
			delete e.charCode;
			_Object_defineProperty(e, {writable: true, configurable: true, value: 9})
			delete e.which;
			_Object_defineProperty(e, {writable: true, configurable: true, value: 9})
			*/
			
			return ((e["keyIdentifier"] || e["key"]) == "+" && (e["keyLocation"] || e["location"]) == 3) && (
				e.ctrlKey ?
					e.altKey ? // webkit
						1
						:
						3
					:
					e.shiftKey ?
						2 // webkit
						:
						4 // IE9
				) || 9 // FireFox|w3c
				;
		}
		catch ( __e__ ) { _initKeyboardEvent_type = 0 }
	})( document.createEvent( "KeyboardEvent" ) )

	, _keyboardEvent_properties_dictionary = {
		"char": "",
		"key": "",
		"location": 0,
		"ctrlKey": false,
		"shiftKey": false,
		"altKey": false,
		"metaKey": false,
		"repeat": false,
		"locale": "",

		"detail": 0,
		"bubbles": false,
		"cancelable": false,
		
		//legacy properties
		"keyCode": 0,
		"charCode": 0,
		"which": 0
	}

	, own = Function.prototype.call.bind(Object.prototype.hasOwnProperty)

	, _Object_defineProperty = Object.defineProperty || function(obj, prop, val) {
		if( "value" in val ) {
			obj[prop] = val["value"];
		}
	}
;

function crossBrowser_initKeyboardEvent(type, dict) {
	var e;
	if( _initKeyboardEvent_type ) {
		e = document.createEvent( "KeyboardEvent" );
	}
	else {
		e = document.createEvent( "Event" );
	}
	var _prop_name
		, localDict = {};

	for( _prop_name in _keyboardEvent_properties_dictionary ) if(own(_keyboardEvent_properties_dictionary, _prop_name) ) {
		localDict[_prop_name] = (own(dict, _prop_name) && dict || _keyboardEvent_properties_dictionary)[_prop_name];
	}

	var _ctrlKey = localDict["ctrlKey"]
		, _shiftKey = localDict["shiftKey"]
		, _altKey = localDict["altKey"]
		, _metaKey = localDict["metaKey"]
		, _altGraphKey = localDict["altGraphKey"]

		, _modifiersListArg = _initKeyboardEvent_type > 3 ? (
			(_ctrlKey ? "Control" : "")
				+ (_shiftKey ? " Shift" : "")
				+ (_altKey ? " Alt" : "")
				+ (_metaKey ? " Meta" : "")
				+ (_altGraphKey ? " AltGraph" : "")
			).trim() : null

		, _key = localDict["key"] + ""
		, _char = localDict["char"] + ""
		, _location = localDict["location"]
		, _keyCode = localDict["keyCode"] || (localDict["keyCode"] = _key && _key.charCodeAt( 0 ) || 0)
		, _charCode = localDict["charCode"] || (localDict["charCode"] = _char && _char.charCodeAt( 0 ) || 0)

		, _bubbles = localDict["bubbles"]
		, _cancelable = localDict["cancelable"]

		, _repeat = localDict["repeat"]
		, _locale = localDict["locale"]
		, _view = global
	;
	
	localDict["which"] || (localDict["which"] = localDict["keyCode"]);

	if( "initKeyEvent" in e ) {//FF
		//https://developer.mozilla.org/en/DOM/event.initKeyEvent
		e.initKeyEvent( type, _bubbles, _cancelable, _view, _ctrlKey, _altKey, _shiftKey, _metaKey, _keyCode, _charCode );
	}
	else if(  _initKeyboardEvent_type && "initKeyboardEvent" in e ) {//https://developer.mozilla.org/en/DOM/KeyboardEvent#initKeyboardEvent()
		if( _initKeyboardEvent_type == 1 ) { // webkit
			//http://stackoverflow.com/a/8490774/1437207
			//https://bugs.webkit.org/show_bug.cgi?id=13368
			e.initKeyboardEvent( type, _bubbles, _cancelable, _view, _key, _location, _ctrlKey, _shiftKey, _altKey, _metaKey, _altGraphKey );
		}
		else if( _initKeyboardEvent_type == 2 ) { // old webkit
			//http://code.google.com/p/chromium/issues/detail?id=52408
			e.initKeyboardEvent( type, _bubbles, _cancelable, _view, _ctrlKey, _altKey, _shiftKey, _metaKey, _keyCode, _charCode );
		}
		else if( _initKeyboardEvent_type == 3 ) { // webkit
			e.initKeyboardEvent( type, _bubbles, _cancelable, _view, _key, _location, _ctrlKey, _altKey, _shiftKey, _metaKey, _altGraphKey );
		}
		else if( _initKeyboardEvent_type == 4 ) { // IE9
			//http://msdn.microsoft.com/en-us/library/ie/ff975297(v=vs.85).aspx
			e.initKeyboardEvent( type, _bubbles, _cancelable, _view, _key, _location, _modifiersListArg, _repeat, _locale );
		}
		else { // FireFox|w3c
			//http://www.w3.org/TR/DOM-Level-3-Events/#events-KeyboardEvent-initKeyboardEvent
			//https://developer.mozilla.org/en/DOM/KeyboardEvent#initKeyboardEvent()
			e.initKeyboardEvent( type, _bubbles, _cancelable, _view, _char, _key, _location, _modifiersListArg, _repeat, _locale );
		}
	}
	else {
		e.initEvent(type, _bubbles, _cancelable)
	}

	for( _prop_name in _keyboardEvent_properties_dictionary )if( own( _keyboardEvent_properties_dictionary, _prop_name ) ) {
		if( e[_prop_name] != localDict[_prop_name] ) {
			try {
				delete e[_prop_name];
				_Object_defineProperty( e, _prop_name, { writable: true, "value": localDict[_prop_name] } );
			}
			catch(e) {
				//Some properties is read-only
			}
			
		}
	}
	
	return e;
}

//export
global.crossBrowser_initKeyboardEvent = crossBrowser_initKeyboardEvent;

}.call(this);

index.html

<html>
  <script src="crossBrowser_initKeyboardEvent.js"></script>
  
  <script>
    var a = window.crossBrowser_initKeyboardEvent("keypress", {"key": 1, "char": "!", shiftKey: true})
    alert(a.type + " | " + a.key + " | " + a.char + " | " + a.shiftKey)
  </script>
</html>