A code that will make sure you enqueue your custom scripts only on pages you need.

is_admin.php

<?php

if ( !function_exists('mytheme_is_admin_page') ) {
    function mytheme_is_admin_page($new_edit = null){
        global $pagenow;

        if (!is_admin()) return false;

        if($new_edit == "edit") { // if is edit post page
            return in_array( $pagenow, array( 'post.php',  ) );
        } elseif($new_edit == "new") { // if is new post page
            return in_array( $pagenow, array( 'post-new.php' ) );
        } elseif($new_edit == "upload") { // if is media page
            return in_array( $pagenow, array( 'upload.php' ) );
        } elseif($new_edit == "options") { // if is settings page
            return in_array( $pagenow, array( 'options-general.php' ) );
        } else {
            return in_array( $pagenow, array( 'post.php', 'post-new.php', 'upload.php', 'options-general.php' ) );
        }
    }
}

// Only enqueue backend styles/scripts if on certain page(s)

if ( travelnews_is_admin_page('new') || travelnews_is_admin_page('edit') ) {
    add_action('admin_enqueue_scripts', 'mytheme_backend_scripts');
}