Landing pull request 503. 1.7 data: set a flag in the private data cache to avoid having to scan attributes multiple times - Fixes #8909.

More Details:
 - https://github.com/jquery/jquery/pull/503
 - http://bugs.jquery.com/ticket/8909

2 files changed, 27 insertions, 4 deletions

diff --git a/src/data.js b/src/data.js
index 9de0da1c5..1c6d1852c 100644
--- a/src/data.js
+++ b/src/data.js
@@ -231,14 +231,15 @@ jQuery.extend({
 
 jQuery.fn.extend({
 	data: function( key, value ) {
-		var data = null;
+		var parts, attr, name,
+			data = null;
 
 		if ( typeof key === "undefined" ) {
 			if ( this.length ) {
 				data = jQuery.data( this[0] );
 
-				if ( this[0].nodeType === 1 ) {
-			    var attr = this[0].attributes, name;
+				if ( this[0].nodeType === 1 && !jQuery._data( this[0], "parsedAttrs" ) ) {
+					attr = this[0].attributes;
 					for ( var i = 0, l = attr.length; i < l; i++ ) {
 						name = attr[i].name;
 
@@ -248,6 +249,7 @@ jQuery.fn.extend({
 							dataAttr( this[0], name, data[ name ] );
 						}
 					}
+					jQuery._data( this[0], "parsedAttrs", true );
 				}
 			}
 
@@ -259,7 +261,7 @@ jQuery.fn.extend({
 			});
 		}
 
-		var parts = key.split(".");
+		parts = key.split(".");
 		parts[1] = parts[1] ? "." + parts[1] : "";
 
 		if ( value === undefined ) {
diff --git a/test/unit/data.js b/test/unit/data.js
index ebeb1b4ee..4feba32c0 100644
--- a/test/unit/data.js
+++ b/test/unit/data.js
@@ -599,3 +599,24 @@ test("Triggering the removeData should not throw exceptions. (#10080)", function
 	// change the url to trigger unload
 	frame.attr("src", "data/iframe.html?param=true");
 });
+
+test( "Only check element attributes once when calling .data() - #8909", function() {
+	expect( 2 );
+	var testing = {
+			test: "testing",
+			test2: "testing"
+		},
+		element = jQuery( "<div data-test='testing'>" ),
+		node = element[ 0 ];
+
+	// set an attribute using attr to ensure it
+	node.setAttribute( "data-test2", "testing" );
+	deepEqual( element.data(), testing, "Sanity Check" );
+
+	node.setAttribute( "data-test3", "testing" );
+	deepEqual( element.data(), testing, "The data didn't change even though the data-* attrs did" );
+
+	// clean up data cache
+	element.remove();
+
+});