<!DOCTYPE html>
<script>
  const blob = new Blob([1, 2]);
  const readable = blob.stream()
  const writable = new WritableStream({}, {
    size() {
      let xhr = new XMLHttpRequest()
      xhr.open("POST", "1", false)
      xhr.send()
    }
  })
  readable.pipeThrough({ readable, writable })
</script>
