Async Generator Control Flow with Symbol.asyncIterator for Chunked Stream Transformations in Next.js

export class ChunkStreamConsumer {
  constructor(readableStream) {
    this.reader = readableStream.getReader();
  }
 
  async *[Symbol.asyncIterator]() {
    try {
      while (true) {
        const { done, value } = await this.reader.read();
        if (done) break;
        yield value;
      }
    } finally {
      this.reader.releaseLock();
    }
  }
}
 
export async function POST(req) {
  const consumer = new ChunkStreamConsumer(req.body);
  let totalBytes = 0;
  for await (const chunk of consumer) {
    totalBytes += chunk.byteLength;
  }
  return Response.json({ processedBytes: totalBytes });
}