How we built it

Fetch API: Response construction with ReadableStream

Developers can now construct their own ReadableStream instances, and use one as a body for constructing a Response object. It enables streaming composed body data from a ServiceWorker to a page controlled by it.


Since M43, readable streams can be obtained (only) from the body attribute of the Response. Developers can now construct their own ReadableStream instances (, and use one for constructing a Response and serve it from a ServiceWorker. This feature had been available behind a flag since M49. A *Request* cannot yet be constructed with a ReadableStream as a body (for streaming uploads).




Working draft or equivalent

Status in Chromium

Enabled by default (launch bug) in:

  • Chrome for desktop release 52
  • Chrome for Android release 52
  • Android WebView release 52
  • Opera release 39
  • Opera for Android release 39

Consensus & Standardization


Last updated on 2016-08-17