Data: always camelCase keys in .data()

- This effectively implements our "Embrace HTML5" option
- Related: http://goo.gl/GcQAtn

Fixes gh-2257

src/data.js

@@ -111,32 +111,25 @@ jQuery.fn.extend({
 		}
 
 		return access( this, function( value ) {
-			var data, camelKey;
+			var data;
 
 			// The calling jQuery object (element matches) is not empty
 			// (and therefore has an element appears at this[ 0 ]) and the
 			// `value` parameter was not undefined. An empty jQuery object
 			// will result in `undefined` for elem = this[ 0 ] which will
 			// throw an exception if an attempt to read a data cache is made.
 			if ( elem && value === undefined ) {
-				// Attempt to get data from the cache
-				// with the key as-is
-				data = dataUser.get( elem, key );
-				if ( data !== undefined ) {
-					return data;
-				}
 
-				camelKey = jQuery.camelCase( key );
 				// Attempt to get data from the cache
-				// with the key camelized
-				data = dataUser.get( elem, camelKey );
+				// The key will always be camelCased in Data
+				data = dataUser.get( elem, key );
 				if ( data !== undefined ) {
 					return data;
 				}
 
 				// Attempt to "discover" the data in
 				// HTML5 custom data-* attrs
-				data = dataAttr( elem, camelKey, undefined );
+				data = dataAttr( elem, key );
 				if ( data !== undefined ) {
 					return data;
 				}
@@ -146,23 +139,10 @@ jQuery.fn.extend({
 			}
 
 			// Set the data...
-			camelKey = jQuery.camelCase( key );
 			this.each(function() {
-				// First, attempt to store a copy or reference of any
-				// data that might've been store with a camelCased key.
-				var data = dataUser.get( this, camelKey );
-
-				// For HTML5 data-* attribute interop, we have to
-				// store property names with dashes in a camelCase form.
-				// This might not apply to all properties...*
-				dataUser.set( this, camelKey, value );
-
-				// *... In the case of properties that might _actually_
-				// have dashes, we need to also store a copy of that
-				// unchanged property.
-				if ( key.indexOf("-") > -1 && data !== undefined ) {
-					dataUser.set( this, key, value );
-				}
+
+				// We always store the camelCased key
+				dataUser.set( this, key, value );
 			});
 		}, null, value, arguments.length > 1, null, true );
 	},

src/data/Data.js

@@ -34,6 +34,7 @@ Data.prototype = {
 		return owner[ this.expando ];
 	},
 	cache: function( owner, initial ) {
+
 		// We can accept data for non-element nodes in modern browsers,
 		// but we should not, see #8335.
 		// Always return an empty object.
@@ -57,14 +58,16 @@ Data.prototype = {
 			cache = this.cache( owner );
 
 		// Handle: [ owner, key, value ] args
+		// Always use camelCase key (gh-2257)
 		if ( typeof data === "string" ) {
-			cache[ data ] = value;
+			cache[ jQuery.camelCase( data ) ] = value;
 
 		// Handle: [ owner, { properties } ] args
 		} else {
+
 			// Copy the properties one-by-one to the cache object
 			for ( prop in data ) {
-				cache[ prop ] = data[ prop ];
+				cache[ jQuery.camelCase( prop ) ] = data[ prop ];
 			}
 		}
 		return cache;
@@ -73,10 +76,13 @@ Data.prototype = {
 		var cache = this.cache( owner );
 
 		return key === undefined ?
-			cache : cache[ key ];
+			cache :
+
+			// Always use camelCase key (gh-2257)
+			cache[ jQuery.camelCase( key ) ];
 	},
 	access: function( owner, key, value ) {
-		var stored;
+
 		// In cases where either:
 		//
 		//   1. No key was specified
@@ -89,12 +95,9 @@ Data.prototype = {
 		//   2. The data stored at the key
 		//
 		if ( key === undefined ||
-				((key && typeof key === "string") && value === undefined) ) {
+				( ( key && typeof key === "string" ) && value === undefined ) ) {
 
-			stored = this.get( owner, key );
-
-			return stored !== undefined ?
-				stored : this.get( owner, jQuery.camelCase(key) );
+			return this.get( owner, key );
 		}
 
 		// [*]When the key is not a string, or both a key and value
@@ -110,7 +113,7 @@ Data.prototype = {
 		return value !== undefined ? value : key;
 	},
 	remove: function( owner, key ) {
-		var i, name, camel,
+		var i,
 			cache = owner[ this.expando ];
 
 		if ( cache === undefined ) {
@@ -121,33 +124,27 @@ Data.prototype = {
 			this.register( owner );
 
 		} else {
+
 			// Support array or space separated string of keys
 			if ( jQuery.isArray( key ) ) {
-				// If "name" is an array of keys...
-				// When data is initially created, via ("key", "val") signature,
-				// keys will be converted to camelCase.
-				// Since there is no way to tell _how_ a key was added, remove
-				// both plain key and camelCase key. #12786
-				// This will only penalize the array argument path.
-				name = key.concat( key.map( jQuery.camelCase ) );
+
+				// If key is an array of keys...
+				// We always set camelCase keys, so remove that.
+				key = key.map( jQuery.camelCase );
 			} else {
-				camel = jQuery.camelCase( key );
-				// Try the string as a key before any manipulation
-				if ( key in cache ) {
-					name = [ key, camel ];
-				} else {
-					// If a key with the spaces exists, use it.
-					// Otherwise, create an array by matching non-whitespace
-					name = camel;
-					name = name in cache ?
-						[ name ] : ( name.match( rnotwhite ) || [] );
-				}
+				key = jQuery.camelCase( key );
+
+				// If a key with the spaces exists, use it.
+				// Otherwise, create an array by matching non-whitespace
+				key = key in cache ?
+					[ key ] :
+					( key.match( rnotwhite ) || [] );
 			}
 
-			i = name.length;
+			i = key.length;
 
 			while ( i-- ) {
-				delete cache[ name[ i ] ];
+				delete cache[ key[ i ] ];
 			}
 		}
 	},

test/unit/data.js

@@ -587,6 +587,34 @@ test(".data should not miss attr() set data-* with hyphenated property names", f
 	deepEqual( b.data("long-param"), { a: 2 }, "data with property long-param was found, 2" );
 });
 
+test(".data always sets data with the camelCased key (gh-2257)", function() {
+	expect( 18 );
+
+	var div = jQuery("<div>").appendTo("#qunit-fixture"),
+		datas = {
+			"non-empty": "a string",
+			"empty-string": "",
+			"one-value": 1,
+			"zero-value": 0,
+			"an-array": [],
+			"an-object": {},
+			"bool-true": true,
+			"bool-false": false,
+
+			// JSHint enforces double quotes,
+			// but JSON strings need double quotes to parse
+			// so we need escaped double quotes here
+			"some-json": "{ \"foo\": \"bar\" }"
+		};
+
+	jQuery.each( datas, function( key, val ) {
+		div.data( key, val );
+		var allData = div.data();
+		equal( allData[ key ], undefined, ".data does not store with hyphenated keys" );
+		equal( allData[ jQuery.camelCase( key ) ], val, ".data stores the camelCased key" );
+	});
+});
+
 test(".data supports interoperable hyphenated/camelCase get/set of properties with arbitrary non-null|NaN|undefined values", function() {
 
 	var div = jQuery("<div/>", { id: "hyphened" }).appendTo("#qunit-fixture"),
@@ -679,19 +707,18 @@ test(".data supports interoperable removal of properties SET TWICE #13850", func
 	});
 });
 
-test( ".removeData supports removal of hyphenated properties via array (#12786)", function() {
+test( ".removeData supports removal of hyphenated properties via array (#12786, gh-2257)", function() {
 	expect( 4 );
 
 	var div, plain, compare;
 
 	div = jQuery("<div>").appendTo("#qunit-fixture");
 	plain = jQuery({});
 
-	// When data is batch assigned (via plain object), the properties
-	// are not camel cased as they are with (property, value) calls
+	// Properties should always be camelCased
 	compare = {
 		// From batch assignment .data({ "a-a": 1 })
-		"a-a": 1,
+		"aA": 1,
 		// From property, value assignment .data( "b-b", 1 )
 		"bB": 1
 	};
@@ -706,7 +733,6 @@ test( ".removeData supports removal of hyphenated properties via array (#12786)"
 	div.removeData([ "a-a", "b-b" ]);
 	plain.removeData([ "a-a", "b-b" ]);
 
-	// NOTE: Timo's proposal for "propEqual" (or similar) would be nice here
 	deepEqual( div.data(), {}, "Data is empty. (div)" );
 	deepEqual( plain.data(), {}, "Data is empty. (plain)" );
 });