Revert "Attributes: Remove undocumented .toggleClass( boolean ) signature"

This reverts commit 53f798cf4d.

- Turns out this is documented, even if not fully. Need to deprecate before removal.

src/attributes/classes.js

@@ -1,8 +1,9 @@
 define( [
 	"../core",
 	"../var/rnotwhite",
+	"../data/var/dataPriv",
 	"../core/init"
-], function( jQuery, rnotwhite ) {
+], function( jQuery, rnotwhite, dataPriv ) {
 
 var rclass = /[\t\r\n\f]/g;
 
@@ -96,26 +97,60 @@ jQuery.fn.extend( {
 	},
 
 	toggleClass: function( value, stateVal ) {
-		var type = typeof value,
-			classNames = type === "string" ? value.match( rnotwhite ) : [];
+		var type = typeof value;
 
-		return this.each( function( i ) {
-			var className,
-				self = jQuery( this ),
-				c = 0;
+		if ( typeof stateVal === "boolean" && type === "string" ) {
+			return stateVal ? this.addClass( value ) : this.removeClass( value );
+		}
 
-			if ( type === "function" ) {
-				classNames = value.call( this, i, getClass( this ), stateVal )
-					.match( rnotwhite ) || [];
-			}
+		if ( jQuery.isFunction( value ) ) {
+			return this.each( function( i ) {
+				jQuery( this ).toggleClass(
+					value.call( this, i, getClass( this ), stateVal ),
+					stateVal
+				);
+			} );
+		}
 
-			// Toggle individual class names based on presence or stateVal
-			while ( ( className = classNames[ c++ ] ) ) {
+		return this.each( function() {
+			var className, i, self, classNames;
 
-				if ( stateVal === false || stateVal !== true && self.hasClass( className ) ) {
-					self.removeClass( className );
-				} else {
-					self.addClass( className );
+			if ( type === "string" ) {
+
+				// Toggle individual class names
+				i = 0;
+				self = jQuery( this );
+				classNames = value.match( rnotwhite ) || [];
+
+				while ( ( className = classNames[ i++ ] ) ) {
+
+					// Check each className given, space separated list
+					if ( self.hasClass( className ) ) {
+						self.removeClass( className );
+					} else {
+						self.addClass( className );
+					}
+				}
+
+			// Toggle whole class name
+			} else if ( value === undefined || type === "boolean" ) {
+				className = getClass( this );
+				if ( className ) {
+
+					// Store className if set
+					dataPriv.set( this, "__className__", className );
+				}
+
+				// If the element has a class name or if we're passed `false`,
+				// then remove the whole classname (if there was one, the above saved it).
+				// Otherwise bring back whatever was previously saved (if anything),
+				// falling back to the empty string if nothing was stored.
+				if ( this.setAttribute ) {
+					this.setAttribute( "class",
+						className || value === false ?
+						"" :
+						dataPriv.get( this, "__className__" ) || ""
+					);
 				}
 			}
 		} );

test/unit/attributes.js

@@ -1239,7 +1239,7 @@ QUnit.test( "removeClass(undefined) is a no-op", function( assert ) {
 } );
 
 var testToggleClass = function( valueObj, assert ) {
-	assert.expect( 11 );
+	assert.expect( 19 );
 
 	var e = jQuery( "#firstp" );
 	assert.ok( !e.is( ".test" ), "Assert class not present" );
@@ -1267,6 +1267,29 @@ var testToggleClass = function( valueObj, assert ) {
 	assert.ok( ( e.is( ".testA.testC" ) && !e.is( ".testB" ) ), "Assert 1 class added, 1 class removed, and 1 class kept" );
 	e.toggleClass( valueObj( "testA testC" ) );
 	assert.ok( ( !e.is( ".testA" ) && !e.is( ".testB" ) && !e.is( ".testC" ) ), "Assert no class present" );
+
+	// toggleClass storage
+	e.toggleClass( true );
+	assert.ok( e[ 0 ].className === "", "Assert class is empty (data was empty)" );
+	e.addClass( "testD testE" );
+	assert.ok( e.is( ".testD.testE" ), "Assert class present" );
+	e.toggleClass();
+	assert.ok( !e.is( ".testD.testE" ), "Assert class not present" );
+	assert.ok( jQuery._data( e[ 0 ], "__className__" ) === "testD testE", "Assert data was stored" );
+	e.toggleClass();
+	assert.ok( e.is( ".testD.testE" ), "Assert class present (restored from data)" );
+	e.toggleClass( false );
+	assert.ok( !e.is( ".testD.testE" ), "Assert class not present" );
+	e.toggleClass( true );
+	assert.ok( e.is( ".testD.testE" ), "Assert class present (restored from data)" );
+	e.toggleClass();
+	e.toggleClass( false );
+	e.toggleClass();
+	assert.ok( e.is( ".testD.testE" ), "Assert class present (restored from data)" );
+
+	// Cleanup
+	e.removeClass( "testD" );
+	assert.expectJqData( this, e[ 0 ], "__className__" );
 };
 
 QUnit.test( "toggleClass(String|boolean|undefined[, boolean])", function( assert ) {