Update cloneCopyEvent so that it does not create superfluous data objects when cloning elements. Exposes a new method, $.hasData. Fixes #7165. Thanks to DaveMethvin and iliakan for their help.

src/data.js

@@ -21,6 +21,14 @@ jQuery.extend({
 		"applet": true
 	},
 
+	hasData: function( elem ) {
+		if ( elem.nodeType ) {
+			elem = jQuery.cache[ elem[jQuery.expando] ];
+		}
+
+		return !!elem && !jQuery.isEmptyObject(elem);
+	},
+
 	data: function( elem, name, data ) {
 		if ( !jQuery.acceptData( elem ) ) {
 			return;

src/manipulation.js

@@ -370,14 +370,18 @@ function root( elem, cur ) {
 }
 
 function cloneCopyEvent(orig, ret) {
-	var i = 0;
-
-	ret.each(function() {
-		if ( this.nodeType !== 1 || this.nodeName !== (orig[i] && orig[i].nodeName) ) {
+	ret.each(function (nodeIndex) {
+		if ( this.nodeType !== 1 || !jQuery.hasData(orig[nodeIndex]) ) {
 			return;
 		}
 
-		var oldData = jQuery.data( orig[i++] ),
+		// XXX remove for 1.5 RC or merge back in if there is actually a reason for this check that has been
+		// unexposed by unit tests
+		if ( this.nodeName !== (orig[nodeIndex] && orig[nodeIndex].nodeName) ) {
+			throw "Cloned data mismatch";
+		}
+
+		var oldData = jQuery.data( orig[nodeIndex] ),
 			curData = jQuery.data( this, oldData ),
 			events = oldData && oldData.events;
 

test/unit/data.js

@@ -78,6 +78,21 @@ test("jQuery.data", function() {
 	ok( jQuery.data( window, "BAD" ), "Make sure that the value was set." );
 });
 
+test("jQuery.hasData", function() {
+	expect(6);
+
+	function testData(obj) {
+		equals( jQuery.hasData(obj), false, "No data exists" );
+		jQuery.data( obj, "foo", "bar" );
+		equals( jQuery.hasData(obj), true, "Data exists" );
+		jQuery.removeData( obj, "foo" );
+		equals( jQuery.hasData(obj), false, "Data was removed" );
+	}
+
+	testData(document.createElement('div'));
+	testData({});
+});
+
 test(".data()", function() {
 	expect(5);
 

test/unit/manipulation.js

@@ -51,7 +51,7 @@ test("text(Function) with incoming value", function() {
 });
 
 var testWrap = function(val) {
-	expect(18);
+	expect(19);
 	var defaultText = 'Try them out:'
 	var result = jQuery('#first').wrap(val( '<div class="red"><span></span></div>' )).text();
 	equals( defaultText, result, 'Check for wrapping of on-the-fly html' );
@@ -80,10 +80,20 @@ var testWrap = function(val) {
 	equals( jQuery("#nonnodes > i").text(), j.text(), "Check node,textnode,comment wraps doesn't hurt text" );
 
 	// Try wrapping a disconnected node
+	var cacheLength = 0;
+	for (var i in jQuery.cache) {
+		cacheLength++;
+	}
+
 	j = jQuery("<label/>").wrap(val( "<li/>" ));
 	equals( j[0].nodeName.toUpperCase(), "LABEL", "Element is a label" );
 	equals( j[0].parentNode.nodeName.toUpperCase(), "LI", "Element has been wrapped" );
 
+	for (i in jQuery.cache) {
+		cacheLength--;
+	}
+	equals(cacheLength, 0, "No memory leak in jQuery.cache (bug #7165)");
+
 	// Wrap an element containing a text node
 	j = jQuery("<span/>").wrap("<div>test</div>");
 	equals( j[0].previousSibling.nodeType, 3, "Make sure the previous node is a text element" );
@@ -856,7 +866,7 @@ test("replaceAll(String|Element|Array&lt;Element&gt;|jQuery)", function() {
 });
 
 test("clone()", function() {
-	expect(36);
+	expect(37);
 	equals( 'This is a normal link: Yahoo', jQuery('#en').text(), 'Assert text for #en' );
 	var clone = jQuery('#yahoo').clone();
 	equals( 'Try them out:Yahoo', jQuery('#first').append(clone).text(), 'Check for clone' );
@@ -914,10 +924,12 @@ test("clone()", function() {
 	equals( clone.html(), div.html(), "Element contents cloned" );
 	equals( clone[0].nodeName.toUpperCase(), "DIV", "DIV element cloned" );
 
-	div = jQuery("<div/>").data({ a: true, b: true });
-	div = div.clone(true);
-	equals( div.data("a"), true, "Data cloned." );
-	equals( div.data("b"), true, "Data cloned." );
+	div = jQuery("<div/>").data({ a: true });
+	var div2 = div.clone(true);
+	equals( div2.data("a"), true, "Data cloned." );
+	div2.data("a", false);
+	equals( div2.data("a"), false, "Ensure cloned element data object was correctly modified" );
+	equals( div.data("a"), true, "Ensure cloned element data object is copied, not referenced" );
 
 	var form = document.createElement("form");
 	form.action = "/test/";