Revert "Core: Throw an error on $("#") rather than returning 0-length collection"

This reverts commit 93f95c9.

Author: markelog

src/core/init.js

@@ -12,8 +12,7 @@ var rootjQuery,
 	// A simple way to check for HTML strings
 	// Prioritize #id over <tag> to avoid XSS via location.hash (#9521)
 	// Strict HTML recognition (#11290: must start with <)
-	// Shortcut simple #id case for speed
-	rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]+))$/,
+	rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]*))$/,
 
 	init = jQuery.fn.init = function( selector, context, root ) {
 		var match, elem;

test/unit/core.js

@@ -56,18 +56,11 @@ QUnit.test( "jQuery()", function( assert ) {
 	assert.expect( expected );
 
 	// Basic constructor's behavior
-	assert.equal( jQuery().length, 0, "jQuery() === jQuery([])" );
-	assert.equal( jQuery( undefined ).length, 0, "jQuery(undefined) === jQuery([])" );
-	assert.equal( jQuery( null ).length, 0, "jQuery(null) === jQuery([])" );
-	assert.equal( jQuery( "" ).length, 0, "jQuery('') === jQuery([])" );
-	assert.deepEqual( jQuery( obj ).get(), obj.get(), "jQuery(jQueryObj) == jQueryObj" );
-
-	// Invalid #id goes to Sizzle which will throw an error (gh-1682)
-	try {
-		jQuery( "#" );
-	} catch ( e ) {
-		assert.ok( true, "Threw an error on #id with no id" );
-	}
+	equal( jQuery().length, 0, "jQuery() === jQuery([])" );
+	equal( jQuery(undefined).length, 0, "jQuery(undefined) === jQuery([])" );
+	equal( jQuery(null).length, 0, "jQuery(null) === jQuery([])" );
+	equal( jQuery("").length, 0, "jQuery('') === jQuery([])" );
+	equal( jQuery("#").length, 0, "jQuery('#') === jQuery([])" );
 
 	// can actually yield more than one, when iframes are included, the window is an array as well
 	assert.equal( jQuery( window ).length, 1, "Correct number of elements generated for jQuery(window)" );