Re: [fetch] Proposed backward-incompatible change: requiring cloning all requests/responses (#61)

So:

* `fetch(req)` considers the body to be optional
* `cache.put(req, res)` requires the `req` body to be null (enforced by `GET`), and the `res` body to be not-null
* `r.json()` etc require the body to be not-null (this would be a change)
* `caches.match(req)` does not use the body of `req`
* Methods that use the body, only mark it as used if it's not-null (or reject/throw if body is required)

So a method that takes a request/response can be described as one of:

* **Does not use body** - so `bodyUsed` has no impact
* **Requires body** - throws if `bodyUsed` is true, otherwise sets `bodyUsed`
* **Considers body** - throws if `bodyUsed` is true, otherwise sets `bodyUsed` if body is present

---
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/61#issuecomment-115180401