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.




Specification link

Specification currently under development in a Working Group

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.



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).

Search tags

streams, fetch, readable streams, streaming,

Last updated on 2020-11-09