fixup! Attributes: Restore boolean attribute & false setter treatment from 3.x

Author: mgol

src/jquery/attributes.js

@@ -30,7 +30,8 @@ jQuery.each( booleans.split( "|" ), function( _i, name ) {
 				attrValue = elem.getAttribute( name );
 
 				if ( attrValue !== name && attrValue != null &&
-					( extraBoolAttrValues[ name ] || [] ).indexOf( attrValue ) === -1
+					( extraBoolAttrValues[ name ] || [] )
+						.indexOf( String( attrValue ).toLowerCase() ) === -1
 				) {
 					migrateWarn( "boolean-attributes",
 						"Boolean attribute '" + name +
@@ -53,7 +54,8 @@ jQuery.each( booleans.split( "|" ), function( _i, name ) {
 		set: origAttrHooks.set || function( elem, value, name ) {
 			if ( jQuery.migrateIsPatchEnabled( "boolean-attributes" ) ) {
 				if ( value !== name &&
-					( extraBoolAttrValues[ name ] || [] ).indexOf( value ) === -1
+					( extraBoolAttrValues[ name ] || [] )
+						.indexOf( String( value ).toLowerCase() ) === -1
 				) {
 					if ( value !== false ) {
 						migrateWarn( "boolean-attributes",

test/unit/jquery/attributes.js

@@ -12,7 +12,7 @@ QUnit.module( "attributes" );
 		QUnit.test( ".attr( boolean attribute ) - patch " +
 				( patchEnabled ? "enabled" : "disabled" ),
 				function( assert ) {
-			assert.expect( 31 );
+			assert.expect( 33 );
 
 			if ( !patchEnabled ) {
 				jQuery.migrateDisablePatches( "boolean-attributes" );
@@ -187,6 +187,23 @@ QUnit.module( "attributes" );
 					"Setting aria attributes to false is not affected by boolean settings"
 				);
 			} );
+
+			expectNoWarning( assert, "extra ex-boolean attrs values", function() {
+				var $input = jQuery( "<input />" );
+
+				$input.attr( "hidden", "until-found" );
+
+				if ( jQueryVersionSince( "4.0.0" ) ) {
+					assert.equal(
+						$input.attr( "hidden" ),
+						"until-found",
+						"Extra values of ex-boolean attributes are not changed"
+					);
+				} else {
+					assert.ok( true,
+						"Extra ex-boolean attrs values not supported under jQuery 3.x" );
+				}
+			} );
 		} );
 	}