Remove specific javascript when viewing page in Customizer?

add_action have 4 parameters, the third one being priority ($priority). Usually plugins and child themes load their scripts after a parent theme to ensure that it doesn’t get overrun later on. So it is wise and good practice to run your action dead last. To to this, you will need a very low priority, ie very high number.

add_action( ‘wp_enqueue_scripts’, ‘jquery_loadup’, 999 );