WP_Customize_Setting::sanitize PHP Method

    public function sanitize($value)
    {
        /**
         * Filters a Customize setting value in un-slashed form.
         *
         * @since 3.4.0
         *
         * @param mixed                $value Value of the setting.
         * @param WP_Customize_Setting $this  WP_Customize_Setting instance.
         */
        return apply_filters("customize_sanitize_{$this->id}", $value, $this);
    }

 /**
  * Returns the sanitized value for a given setting from the request's POST data.
  *
  * @since 3.4.0
  * @since 4.1.1 Introduced the `$default` parameter.
  * @since 4.6.0 `$default` is now returned early when the setting post value is invalid.
  * @access public
  *
  * @see WP_REST_Server::dispatch()
  * @see WP_Rest_Request::sanitize_params()
  * @see WP_Rest_Request::has_valid_params()
  *
  * @param WP_Customize_Setting $setting A WP_Customize_Setting derived object.
  * @param mixed                $default Value returned $setting has no post value (added in 4.2.0)
  *                                      or the post value is invalid (added in 4.6.0).
  * @return string|mixed $post_value Sanitized value or the $default provided.
  */
 public function post_value($setting, $default = null)
 {
     $post_values = $this->unsanitized_post_values();
     if (!array_key_exists($setting->id, $post_values)) {
         return $default;
     }
     $value = $post_values[$setting->id];
     $valid = $setting->validate($value);
     if (is_wp_error($valid)) {
         return $default;
     }
     $value = $setting->sanitize($value);
     if (is_null($value) || is_wp_error($value)) {
         return $default;
     }
     return $value;
 }