There are probably various ways to do this – personally I use the following for loading some small scripts only on the “new” and “edit” pages (datepicker etc.):
function load_my_admin_scripts( $hook ) {
if (( $hook == 'post.php' || $hook == 'post-new.php' )) {
wp_enqueue_script(
'my-datepicker', // name / handle of the script
SCRIPTS . 'script.js', // path to the script
array( 'jquery', 'jquery-ui-datepicker' ), // array of registered handles this script depends on
'1.0', // script version number (optional)
true // enqueue the script before </head>
);
}
}
add_action( 'admin_enqueue_scripts', 'load_my_admin_scripts' );