Bootstrap4 materialized scripts

// Register Script
function custom_scripts() {

	wp_register_script( 'bootstrap4_thether', '//cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js', false, '1.4.0', true );
	wp_enqueue_script( 'bootstrap4_thether' );

	wp_register_script( 'bootstrap4_alpha6', '//maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js', false, '4.0.0.6', true );
	wp_enqueue_script( 'bootstrap4_alpha6' );

}
add_action( 'wp_enqueue_scripts', 'custom_scripts' );