next: async()

in packages/dubbo-web/src/grpc-web-transport.ts [159:209]

• 40 lines of code
• 7 McCabe index (conditional complexity)

        next: async (req: UnaryRequest<I, O>): Promise<UnaryResponse<I, O>> => {
          const response = await fetch(req.url, {
            ...req.init,
            headers: req.header,
            signal: req.signal,
            body: encodeEnvelope(0, serialize(req.message)),
          });
          validateResponse(response.status, response.headers);
          if (!response.body) {
            throw "missing response body";
          }
          const reader = createEnvelopeReadableStream(
            response.body
          ).getReader();
          let trailer: Headers | undefined;
          let message: O | undefined;
          for (;;) {
            const r = await reader.read();
            if (r.done) {
              break;
            }
            const { flags, data } = r.value;
            if (flags === trailerFlag) {
              if (trailer !== undefined) {
                throw "extra trailer";
              }
              // Unary responses require exactly one response message, but in
              // case of an error, it is perfectly valid to have a response body
              // that only contains error trailers.
              trailer = trailerParse(data);
              continue;
            }
            if (message !== undefined) {
              throw "extra message";
            }
            message = parse(data);
          }
          if (trailer === undefined) {
            throw "missing trailer";
          }
          validateTrailer(trailer);
          if (message === undefined) {
            throw "missing message";
          }
          return <UnaryResponse<I, O>>{
            stream: false,
            header: response.headers,
            message,
            trailer,
          };
        },