This a re-post since my original "question-answer" were deleted in this directly-related thread.
How do you read "merged" multi cookies from Fetch API, especially when containing Expiration dates ?
We tried with request.headers.get('cookie').split(',')
where :
Cookie: cookie1=value1; Path=/; Expires=Tue, 04 Aug 2020 19:45:53 GMT; HttpOnly, cookie2=value2; Path=/; Expires=Tue, 05 Sept 2020 14:32:03 GMT; HttpOnly
... but obviously this fails because of the comma in the dates.
Context: i'm trying to promote native fetch to my teams currently using XMLHttpRequests, but they are reluctant because of this -very frequent- expires issue.