Add Zyyy for an undetermined script and use it accordingly

data/langdb.yaml

@@ -544,6 +544,8 @@ scriptgroups:
   Mongolian: [Mong]
   SignWriting: [Sgnw]
   NativeAmerican: [Cher, Cans]
+ # Undetermined script
+  Special: [Zyyy]
 
 rtlscripts:
   [Arab, Hebr, Syrc, Nkoo, Thaa]

src/jquery.uls.data.utils.js

@@ -42,6 +42,11 @@
 			return $.uls.data.getScript( target );
 		}
 
+		if ( !$.uls.data.languages[language] ) {
+			// Undetermined
+			return 'Zyyy';
+		}
+
 		return $.uls.data.languages[language][0];
 	};
 

test/jquery.uls.test.js

@@ -97,7 +97,7 @@
 		assert.ok( $.fn.uls, '$.fn.uls is defined' );
 	} );
 
-	test( '-- $.uls.data testing', 46, function ( assert ) {
+	test( '-- $.uls.data testing', 47, function ( assert ) {
 		var autonyms,
 			allLanguagesByRegionAndScript,
 			languagesInEU,
@@ -141,6 +141,7 @@
 			'The script of the Inupiaq language belongs to the NativeAmerican group.'
 		);
 
+		assert.strictEqual( $.uls.data.getScript( 'no-such-language' ), 'Zyyy', 'A script for an unknown language is Zyyy - undetermined' );
 		assert.strictEqual( $.uls.data.getScript( 'ii' ), 'Yiii', 'Correct script of the Yi language was selected' );
 		assert.deepEqual( $.uls.data.getRegions( 'lzz' ), [
 			'EU', 'ME'