CODE EXAMPLE FOR PHP

how to add script in WordPress admin page

/**
 * Enqueue a script in the WordPress admin on edit.php.
 *
 * @param int $hook Hook suffix for the current admin page.
 */
function wpdocs_selectively_enqueue_admin_script( $hook ) {
    if ( 'edit.php' != $hook ) {
        return;
    }
    wp_enqueue_script( 'my_custom_script', plugin_dir_url( __FILE__ ) . 'myscript.js', array(), '1.0' );
}
add_action( 'admin_enqueue_scripts', 'wpdocs_selectively_enqueue_admin_script' );