Add some comments to the code

src/jquery.uls.languagefilter.js

@@ -106,6 +106,8 @@
 
 					query = ( this.$element.val() || '' ).trim().toLowerCase();
 
+					// Check if a language is currently highlighted, and if so select that
+					// if user presses enter.
 					var highlightedLanguage = this.options.lcd.getHighlightedLanguageCode();
 					if ( highlightedLanguage ) {
 						this.options.onSelect( highlightedLanguage, e );

src/jquery.uls.lcd.js

@@ -150,6 +150,7 @@
 			var $selectedItem = $listItems.eq( this.navigationIndex );
 			$selectedItem.addClass( 'language-option--highlighted' );
 
+			// If the selected item is not visible, then scroll the container to display it
 			if ( !isLanguageFullyVisible( $selectedItem, this.$element ) ) {
 				$selectedItem.get( 0 ).scrollIntoView( false );
 			}