WP REST API v2

function.php

// WP REST API v2

// Prepare Pages 
add_filter('rest_prepare_page', 'remove_extra_data', 12, 3);
function remove_extra_data($data, $post, $context) {
  if ($context !== 'view' || is_wp_error ($data)) {
    unset ($data->data['excerpt']);
    // ...
    return $data;
  }
}

// Prepare Posts
add_filter('rest_prepare_post', 'remove_extra_data', 12, 3);
function remove_extra_data($data, $post, $context) {
  if ($context !== 'view' || is_wp_error($data)) {
    unset($data->data['excerpt']);
    // ...
    return $data;
  }
}

// For Custom Post Type: add_filter('rest_prepare_{$post_type}', 'remove_extra_data', 12, 3);