Fix get unique ID function

inc/mixes-functions.php

@@ -1306,3 +1306,26 @@ function opalestate_clean( $var ) {
 		return is_scalar( $var ) ? sanitize_text_field( $var ) : $var;
 	}
 }
+
+/**
+ * Get unique ID.
+ *
+ * This is a PHP implementation of Underscore's uniqueId method. A static variable
+ * contains an integer that is incremented with each call. This number is returned
+ * with the optional prefix. As such the returned value is not universally unique,
+ * but it is unique across the life of the PHP process.
+ *
+ * @see wp_unique_id() Themes requiring WordPress 5.0.3 and greater should use this instead.
+ *
+ * @staticvar int $id_counter
+ *
+ * @param string $prefix Prefix for the returned ID.
+ * @return string Unique ID.
+ */
+function opalestate_unique_id( $prefix = '' ) {
+	static $id_counter = 0;
+	if ( function_exists( 'wp_unique_id' ) ) {
+		return wp_unique_id( $prefix );
+	}
+	return $prefix . (string) ++$id_counter;
+}