So I have a page select in my theme's customizer and a bit of code to make the preview change when the user selects a different page:

    api('gm_pages', function (setting) {
               var pageID = setting.get();
                setting.bind( function onChange( pageID ) {
                    api.previewer.previewUrl.set(api.settings.url.home + '?page_id=' + pageID);
                   })
            });


I use this simple plugin so user can reset customizer settings to default:


https://plugins.trac.wordpress.org/browser/customizer-reset-by-wpzoom/trunk

When you click a button, you get a warning popup then if you click through it, the plugin deletes the theme_mod data and refreshes the entire site.

The problem I am having is when I do this, the page dropdown option returns to the default "home" page but the preview URL doesn't update and stays on the last page the user had selected. If I console.log(pageID); the correct page number (showing in the select box) shows, it's the preview that doesn't run for some reason.

Edit: I can add this line in: 
   

     if (performance.navigation.type === 1) {
                api.previewer.previewUrl.set(api.settings.url.home + '?page_id=' + pageID);
            }

and that does the trick, but how can I do this conditionally without needing 2 lines of the same code?