The domain {% data variables.product.prodname_dotcom %} uses for port forwarding may change from time to time. If you reference a forwarded port in your code, for example in a test, we recommend that you use an environment variable instead of hardcoding the URL. For more information, see "[AUTOTITLE](/codespaces/developing-in-codespaces/default-environment-variables-for-your-codespace#list-of-default-environment-variables)."