Fixes #7328. When getting data- attributes, after-cap any embedded dashes per the W3C HTML5 spec.

src/data.js

 (function( jQuery ) {
 
-var rbrace = /^(?:\{.*\}|\[.*\])$/;
+var rbrace = /^(?:\{.*\}|\[.*\])$/,
+	rmultiDash = /([a-z])([A-Z])/g;
 
 jQuery.extend({
 	cache: {},
@@ -228,7 +229,8 @@ jQuery.fn.extend({
 						name = attr[i].name;
 
 						if ( name.indexOf( "data-" ) === 0 ) {
-							name = name.substr( 5 );
+							name = jQuery.camelCase( name.substring(5) );
+
 							dataAttr( this[0], name, data[ name ] );
 						}
 					}
@@ -282,7 +284,9 @@ function dataAttr( elem, key, data ) {
 	// If nothing was found internally, try to fetch any
 	// data from the HTML5 data-* attribute
 	if ( data === undefined && elem.nodeType === 1 ) {
-		data = elem.getAttribute( "data-" + key );
+		name = "data-" + key.replace( rmultiDash, "$1-$2" ).toLowerCase();
+
+		data = elem.getAttribute( name );
 
 		if ( typeof data === "string" ) {
 			try {

test/unit/data.js

@@ -486,3 +486,20 @@ if (window.JSON && window.JSON.stringify) {
 		equals( JSON.stringify(obj), '{"foo":"bar"}', "Expando is hidden from JSON.stringify" );
 	});
 }
+
+test("jQuery.data should follow html5 specification regarding camel casing", function() {
+	expect(6);
+
+	var div = jQuery("<div id='myObject' data-foo='a' data-foo-bar='b' data-foo-bar-baz='c'></div>")
+		.prependTo("body");
+
+	equals(div.data().foo, "a", "Verify single word data-* key");
+	equals(div.data().fooBar, "b", "Verify multiple word data-* key");
+	equals(div.data().fooBarBaz, "c", "Verify multiple word data-* key");
+
+	equals(div.data("foo"), "a", "Verify single word data-* key");
+	equals(div.data("fooBar"), "b", "Verify multiple word data-* key");
+	equals(div.data("fooBarBaz"), "c", "Verify multiple word data-* key");
+
+	div.remove();
+});
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