+
+/**
+ * Determines whether the current request is a WordPress Ajax request.
+ *
+ * @since 4.7.0
+ *
+ * @return bool True if it's a WordPress Ajax request, false otherwise.
+ */
+function wp_doing_ajax() {
+ /**
+ * Filters whether the current request is a WordPress Ajax request.
+ *
+ * @since 4.7.0
+ *
+ * @param bool $wp_doing_ajax Whether the current request is a WordPress Ajax request.
+ */
+ return apply_filters( 'wp_doing_ajax', defined( 'DOING_AJAX' ) && DOING_AJAX );
+}
+
+/**
+ * Check whether variable is a WordPress Error.
+ *
+ * Returns true if $thing is an object of the WP_Error class.
+ *
+ * @since 2.1.0
+ *
+ * @param mixed $thing Check if unknown variable is a WP_Error object.
+ * @return bool True, if WP_Error. False, if not WP_Error.
+ */
+function is_wp_error( $thing ) {
+ return ( $thing instanceof WP_Error );
+}