The documentation for mutate talks about local mutation for faster feedback, but the documented way to use it only mutates after a promise has resolved - in other words, not immediately.

As a result, I've found myself writing code in this kind of pattern:

mutate(path, { ...data, patch }, false); // mutate immediately, don't revalidate
await patchData(patch); // await the 

Got has a very good coverage test-wise. Would be nice to port relevant tests that we're missing over to Ky.

Note: Not for https://github.com/sindresorhus/ky/blob/master/test/browser.js, but for everything else.

From time to time i see ppl using data instead of body which is wrong.
happened just recently in node-fetch/node-fetch#481 (comment)

how do you feel about adding a little warning message that can only appear once. (kinda like node reports that you are using experimental apis)

if ('data' in bodyInit && notWarned) {
  console.warn('use body i

Presumably these should result in a network error. The current specification doesn't state anything and it's not tested either.

See the README for instructions on where to add tests. In the specification the "blob" case of https://fetch.spec.whatwg.org/#scheme-fetch needs updating to handle current URL’s blob URL entry being null.