[BUG] Release notes for breaking change to `accept` in v12.0.0 are ambiguous

Describe the bug

I don’t think its clear what the breaking change to accept refers to in https://github.com/react-dropzone/react-dropzone/releases/tag/v12.0.0

Does it, for example, involve a breaking change to the accept prop provided to useDropzone documented here. That uses react-dropzone/attr-accept which does not seem to have changed so I am confused by the release note.

Expected

Clear actions to take when a breaking change is reported in the package.

[rolandjitsu]

Thanks for clarifying that. So to resolve the breaking change I would change as follows?:

useDropzone({
    accept: 'image/jpeg, image/png',
 });

It should change to:

useDropzone({
    accept: { 'image/*': ['.jpeg', '.jpg'] },
 });

Ok, no. Let me try to clarify. When you use accept=".jpg", the file picker when triggered by click, it will not filter because the FS access API expects what you just posted above.

That’s because we do not keep a map of file ext => MIME type. But if you pass mime types accept="image/png", the file picker will work because we internally turn that string into the object that the FS access API needs:

https://github.com/react-dropzone/react-dropzone/blob/df8a9b4231b98fbc8b964c3cf0ca5f8682a50613/src/utils/index.js#L183

So, in summary:

1. the type for accept has not changed; it still takes a string or list of strings
2. in browsers that do not support the FS access API, the accept attr works exactly the same as in previous versions of react-dropozone, for both file picker and dag ‘n’ drop
3. in browser that support the FS access API, when passing file extensions to accept (e.g ".jpg,.png"), the file picker will not apply those filters, but drag ‘n’ drop will
4. the use of FS access API can be turned off via useDropzone({useFsAccessApi: false})

[rolandjitsu]

I’ve created https://github.com/react-dropzone/react-dropzone/pull/1139 which hopefully makes it more clear. See staging docs.