Selector: Re-introduce selector-native.js

Re-introduce the `selector-native` similar to the one on the `3.x-stable`
branch. One difference is since the `main` branch inlined Sizzle, some
selector utils can be shared between the main `selector` module and
`selector-native`.

The main `selector` module can be disabled in favor of `selector-native`
via:

    grunt custom:-selector

Other changes:
* Tests: Fix Safari detection - Chrome Headless has a different user
  agent than Safari and a browser check in selector tests didn't take
  that into account.
* Tests: Run selector-native tests in `npm test`
* Selector: Fix querying on document fragments

Ref gh-4395
Closes gh-5085

.github/workflows/node.js.yml

@@ -25,6 +25,10 @@ jobs:
             NODE_VERSION: "16.x"
             NPM_SCRIPT: "test:no-deprecated"
             BROWSERS: "ChromeHeadless"
+          - NAME: "Browser tests: selector-native build, Chrome stable"
+            NODE_VERSION: "16.x"
+            NPM_SCRIPT: "test:selector-native"
+            BROWSERS: "ChromeHeadless"
           - NAME: "Browser tests: ES modules build, Chrome stable"
             NODE_VERSION: "16.x"
             NPM_SCRIPT: "test:esmodules"

Gruntfile.js

@@ -61,8 +61,7 @@ module.exports = function( grunt ) {
 			all: {
 				dest: "dist/jquery.js",
 				minimum: [
-					"core",
-					"selector"
+					"core"
 				],
 
 				// Exclude specified modules if the module matching the key is removed
@@ -75,7 +74,8 @@ module.exports = function( grunt ) {
 						remove: [ "ajax", "effects", "queue", "core/ready" ],
 						include: [ "core/ready-no-deferred" ]
 					},
-					event: [ "deprecated/ajax-event-alias", "deprecated/event" ]
+					event: [ "deprecated/ajax-event-alias", "deprecated/event" ],
+					selector: [ "css/hiddenVisibleSelectors", "effects/animatedSelector" ]
 				}
 			}
 		},

README.md

@@ -99,6 +99,12 @@ Some example modules that can be excluded are:
 - **exports/global**: Exclude the attachment of global jQuery variables ($ and jQuery) to the window.
 - **exports/amd**: Exclude the AMD definition.
 
+As a special case, you may also replace the full jQuery `selector` module by using a special flag `grunt custom:-selector`.
+
+- **selector**: The full jQuery selector engine. When this module is excluded, it is replaced by a rudimentary selector engine based on the browser's `querySelectorAll` method that does not support jQuery selector extensions or enhanced semantics. See the [selector-native.js](https://github.com/jquery/jquery/blob/main/src/selector-native.js) file for details.
+
+*Note*: Excluding the full `selector` module will also exclude all jQuery selector extensions (such as `effects/animatedSelector` and `css/hiddenVisibleSelectors`).
+
 The build process shows a message for each dependent module it excludes or includes.
 
 ##### AMD name

build/tasks/build.js

@@ -128,11 +128,11 @@ module.exports = function( grunt ) {
 			 * Adds the specified module to the excluded or included list, depending on the flag
 			 * @param {String} flag A module path relative to
 			 *  the src directory starting with + or - to indicate
-			 *  whether it should included or excluded
+			 *  whether it should be included or excluded
 			 */
 			const excluder = flag => {
 				let additional;
-				const m = /^(\+|\-|)([\w\/-]+)$/.exec( flag );
+				const m = /^(\+|-|)([\w\/-]+)$/.exec( flag );
 				const exclude = m[ 1 ] === "-";
 				const module = m[ 2 ];
 
@@ -150,10 +150,16 @@ module.exports = function( grunt ) {
 							// These are the removable dependencies
 							// It's fine if the directory is not there
 							try {
-								excludeList(
-									fs.readdirSync( `${ srcFolder }/${ module }` ),
-									module
-								);
+
+								// `selector` is a special case as we don't just remove
+								// the module, but we replace it with `selector-native`
+								// which re-uses parts of the `src/selector` folder.
+								if ( module !== "selector" ) {
+									excludeList(
+										fs.readdirSync( `${ srcFolder }/${ module }` ),
+										module
+									);
+								}
 							} catch ( e ) {
 								grunt.verbose.writeln( e );
 							}
@@ -232,14 +238,14 @@ module.exports = function( grunt ) {
 				// Remove the comma for anonymous defines
 				setOverride( `${ srcFolder }/exports/amd.js`,
 					read( "exports/amd.js" )
-						.replace( /(\s*)"jquery"(\,\s*)/,
+						.replace( /(\s*)"jquery"(,\s*)/,
 							amdName ? "$1\"" + amdName + "\"$2" : "" ) );
 			}
 
 			grunt.verbose.writeflags( excluded, "Excluded" );
 			grunt.verbose.writeflags( included, "Included" );
 
-			// Indicate a Slim build without listing all of the exclusions
+			// Indicate a Slim build without listing all the exclusions
 			// to save space.
 			if ( isPureSlim ) {
 				version += " slim";
@@ -260,7 +266,13 @@ module.exports = function( grunt ) {
 
 				// Replace excluded modules with empty sources.
 				for ( const module of excluded ) {
-					setOverride( `${ srcFolder }/${ module }.js`, "" );
+					setOverride(
+						`${ srcFolder }/${ module }.js`,
+
+						// The `selector` module is not removed, but replaced
+						// with `selector-native`.
+						module === "selector" ? read( "selector-native.js" ) : ""
+					);
 				}
 			}
 

package.json

@@ -77,8 +77,9 @@
     "test:esmodules": "grunt && grunt karma:esmodules",
     "test:amd": "grunt && grunt karma:amd",
     "test:no-deprecated": "grunt test:prepare && grunt custom:-deprecated && grunt karma:main",
+    "test:selector-native": "grunt test:prepare && grunt custom:-selector && grunt karma:main",
     "test:slim": "grunt test:prepare && grunt custom:slim && grunt karma:main",
-    "test": "npm run test:slim && npm run test:no-deprecated && grunt && grunt test:slow && grunt karma:main && grunt karma:esmodules && grunt karma:amd",
+    "test": "npm run test:slim && npm run test:no-deprecated && npm run test:selector-native && grunt && grunt test:slow && grunt karma:main && grunt karma:esmodules && grunt karma:amd",
     "jenkins": "npm run test:browserless"
   },
   "commitplease": {

src/selector-native.js

@@ -0,0 +1,88 @@
+/*
+ * Optional limited selector module for custom builds.
+ *
+ * Note that this DOES NOT SUPPORT many documented jQuery
+ * features in exchange for its smaller size:
+ *
+ * * Attribute not equal selector (!=)
+ * * Positional selectors (:first; :eq(n); :odd; etc.)
+ * * Type selectors (:input; :checkbox; :button; etc.)
+ * * State-based selectors (:animated; :visible; :hidden; etc.)
+ * * :has(selector)
+ * * :not(complex selector)
+ * * custom selectors via jQuery extensions
+ * * Leading combinators (e.g., $collection.find("> *"))
+ * * Reliable functionality on XML fragments
+ * * Requiring all parts of a selector to match elements under context
+ *     (e.g., $div.find("div > *") now matches children of $div)
+ * * Matching against non-elements
+ * * Reliable sorting of disconnected nodes
+ * * querySelectorAll bug fixes (e.g., unreliable :focus on WebKit)
+ *
+ * If any of these are unacceptable tradeoffs, either use the full
+ * selector engine or  customize this stub for the project's specific
+ * needs.
+ */
+
+import jQuery from "./core.js";
+import document from "./var/document.js";
+import documentElement from "./var/documentElement.js";
+import whitespace from "./var/whitespace.js";
+
+// The following utils are attached directly to the jQuery object.
+import "./selector/contains.js";
+import "./selector/escapeSelector.js";
+import "./selector/uniqueSort.js";
+
+// Support: IE 9 - 11+
+// IE requires a prefix.
+var matches = documentElement.matches || documentElement.msMatchesSelector;
+
+jQuery.extend( {
+	find: function( selector, context, results, seed ) {
+		var elem, nodeType,
+			i = 0;
+
+		results = results || [];
+		context = context || document;
+
+		// Same basic safeguard as in the full selector module
+		if ( !selector || typeof selector !== "string" ) {
+			return results;
+		}
+
+		// Early return if context is not an element, document or document fragment
+		if ( ( nodeType = context.nodeType ) !== 1 && nodeType !== 9 && nodeType !== 11 ) {
+			return [];
+		}
+
+		if ( seed ) {
+			while ( ( elem = seed[ i++ ] ) ) {
+				if ( jQuery.find.matchesSelector( elem, selector ) ) {
+					results.push( elem );
+				}
+			}
+		} else {
+			jQuery.merge( results, context.querySelectorAll( selector ) );
+		}
+
+		return results;
+	},
+	expr: {
+		attrHandle: {},
+		match: {
+			bool: new RegExp( "^(?:checked|selected|async|autofocus|autoplay|controls|defer" +
+				"|disabled|hidden|ismap|loop|multiple|open|readonly|required|scoped)$", "i" ),
+			needsContext: new RegExp( "^" + whitespace + "*[>+~]" )
+		}
+	}
+} );
+
+jQuery.extend( jQuery.find, {
+	matches: function( expr, elements ) {
+		return jQuery.find( expr, null, null, elements );
+	},
+	matchesSelector: function( elem, expr ) {
+		return matches.call( elem, expr );
+	}
+} );

test/data/testinit.js

@@ -301,17 +301,6 @@ if ( !window.__karma__ ) {
 QUnit.isSwarm = ( QUnit.urlParams.swarmURL + "" ).indexOf( "http" ) === 0;
 QUnit.basicTests = ( QUnit.urlParams.module + "" ) === "basic";
 
-// Says whether jQuery positional selector extensions are supported.
-// A full selector engine is required to support them as they need to be evaluated
-// left-to-right. Remove that property when support for positional selectors is dropped.
-QUnit.jQuerySelectorsPos = true;
-
-// Says whether jQuery selector extensions are supported. Change that to `false`
-// if your custom jQuery versions relies more on native qSA.
-// This doesn't include support for positional selectors (see above).
-// TODO do we want to keep this or just assume support for jQuery extensions?
-QUnit.jQuerySelectors = true;
-
 // Support: IE 11+
 // A variable to make it easier to skip specific tests in IE, mostly
 // testing integrations with newer Web features not supported by it.
@@ -388,6 +377,18 @@ this.loadTests = function() {
 
 	// Get testSubproject from testrunner first
 	require( [ parentUrl + "test/data/testrunner.js" ], function() {
+
+		// Says whether jQuery positional selector extensions are supported.
+		// A full selector engine is required to support them as they need to
+		// be evaluated left-to-right. Remove that property when support for
+		// positional selectors is dropped.
+		QUnit.jQuerySelectorsPos = includesModule( "selector" );
+
+		// Says whether jQuery selector extensions are supported. Change that
+		// to `false` if your custom jQuery versions relies more on native qSA.
+		// This doesn't include support for positional selectors (see above).
+		QUnit.jQuerySelectors = includesModule( "selector" );
+
 		var i = 0,
 			tests = [
 				// A special module with basic tests, meant for not fully

test/unit/selector.js

@@ -1,7 +1,7 @@
 QUnit.module( "selector", {
 	beforeEach: function() {
 		this.safari = /\bsafari\b/i.test( navigator.userAgent ) &&
-			!/\bchrome\b/i.test( navigator.userAgent );
+			!/\b(?:headless)?chrome\b/i.test( navigator.userAgent );
 	},
 	afterEach: moduleTeardown
 } );
@@ -1908,6 +1908,21 @@ QUnit.testUnlessIE( "jQuery.contains within <template/> doesn't throw (gh-5147)"
 	assert.ok( true, "Didn't throw" );
 } );
 
+QUnit.test( "find in document fragments", function( assert ) {
+	assert.expect( 1 );
+
+	var elem,
+		nonnodes = jQuery( "#nonnodes" ).contents(),
+		fragment = document.createDocumentFragment();
+
+	nonnodes.each( function() {
+		fragment.appendChild( this );
+	} );
+
+	elem = jQuery( fragment ).find( "#nonnodesElement" );
+	assert.strictEqual( elem.length, 1, "Selection works" );
+} );
+
 QUnit.test( "jQuery.uniqueSort", function( assert ) {
 	assert.expect( 14 );
 
@@ -2156,7 +2171,7 @@ QUnit.test( "jQuery.escapeSelector", function( assert ) {
 	assert.equal( jQuery.escapeSelector( "\uD834" ), "\uD834", "Doesn't escape lone high surrogate" );
 } );
 
-QUnit.test( "custom pseudos", function( assert ) {
+QUnit[ QUnit.jQuerySelectors ? "test" : "skip" ]( "custom pseudos", function( assert ) {
 	assert.expect( 6 );
 
 	try {

test/unit/support.js

@@ -55,7 +55,7 @@ testIframe(
 );
 
 ( function() {
-	var expected,
+	var expected, browserKey,
 		userAgent = window.navigator.userAgent,
 		expectedMap = {
 			ie_11: {
@@ -80,6 +80,13 @@ testIframe(
 			}
 		};
 
+	// Make the selector-native build pass tests.
+	for ( browserKey in expectedMap ) {
+		if ( !includesModule( "selector" ) ) {
+			delete expectedMap[ browserKey ].cssSupportsSelector;
+		}
+	}
+
 	if ( document.documentMode ) {
 		expected = expectedMap.ie_11;
 	} else if ( /chrome/i.test( userAgent ) ) {