Provides the completion status and result of the corresponding asynchronous method call. A failure errorCode will be passed if the content failed to load. E_ABORT means the response loading was blocked (e.g., by CORS policy); ERROR_CANCELLED means the response loading was cancelled. ERROR_NO_DATA means the response has no content data, content is null in this case. Note content (if any) is ignored for redirects, 204 No Content, 205 Reset Content, and HEAD-request responses.