Makes jQuery.event.fix fast

jquery.event.fix.js

// http://bitovi.com/blog/2012/04/faster-jquery-event-fix.html
// https://gist.github.com/2954434 (original: https://gist.github.com/2377196)

// IE 8 has Object.defineProperty but it only defines DOM Nodes. According to
// http://kangax.github.com/es5-compat-table/#define-property-ie-note
// All browser that have Object.defineProperties also support Object.defineProperty properly

Object.defineProperties && (function (document, $){
	var
		// Use defineProperty on an object to set the value and return it
		set = function (obj, prop, val) {
			if( val !== undefined ){
				Object.defineProperty(obj, prop, {
					value : val
				});
			}
			return val;
		},

		// special converters
		special = {
			pageX : function (evt) {
				var
					  eventDoc = this.target.ownerDocument || document
					, doc	= eventDoc.documentElement
					, body	= eventDoc.body
				;
				return evt.clientX + (doc && doc.scrollLeft || body && body.scrollLeft || 0 ) - ( doc && doc.clientLeft || body && body.clientLeft || 0);
			},

			pageY : function (evt) {
				var
					  eventDoc = this.target.ownerDocument || document
					, doc	= eventDoc.documentElement
					, body	= eventDoc.body
				;
				return evt.clientY + (doc && doc.scrollTop || body && body.scrollTop || 0 ) - ( doc && doc.clientTop || body && body.clientTop || 0);
			},

			relatedTarget : function (evt) {
				if(!evt) {
					return;
				}
				return evt.fromElement === this.target ? evt.toElement : evt.fromElement;
			},

			metaKey : function (evt) {
				return evt.ctrlKey;
			},

			which : function (evt) {
				return evt.charCode != null ? evt.charCode : evt.keyCode;
			}
		}
	;


	// support jQuery < 1.7
	if( !$.event.keyHooks )		$.event.keyHooks	= { props: [] };
	if( !$.event.mouseHooks )	$.event.mouseHooks	= { props: [] };


	// Get all properties that should be mapped
	$.each($.event.keyHooks.props.concat($.event.mouseHooks.props, $.event.props), function (i, prop) {
		if( prop !== "target" ){
			(function (){
				Object.defineProperty($.Event.prototype, prop, {
					get : function () {
						// get the original value, undefined when there is no original event
						var originalValue = this.originalEvent && this.originalEvent[prop];

						// overwrite getter lookup
						return this['_' + prop] !== undefined ? this['_' + prop] : set(this, prop,
							// if we have a special function and no value
							special[prop] && originalValue === undefined ?
								// call the special function
								special[prop].call(this, this.originalEvent) :
								// use the original value
								originalValue)
					},

					set : function (newValue) {
						// Set the property with underscore prefix
						this['_' + prop] = newValue;
					}
				});
			})();
		}
	});


	$.event.fix = function (evt) {
		if( evt[ $.expando ] ){
			return	evt;
		}

		// Create a jQuery event with at minimum a target and type set
		var original = evt, target = original.target;

		evt = $.Event(original);

		// Fix target property, if necessary (#1925, IE 6/7/8 & Safari2)
		if( !target ){
			target = original.srcElement || document;
		}

		// Target should not be a text node (#504, Safari)
		if( target.nodeType === 3 ){
			target = target.parentNode;
		}

		evt.target = target;

		return	evt;
	}
})(document, jQuery);

https://gist.github.com/2954434/dfe49ed76d54281a12992c2df78b84b0a0725d87

changelog

• support jQuery < 1.7
• fixed special.pageX and special.pageY