Fetch can take an init object containing many custom settings that you might want to apply to the request, this includes an option called “headers”. The “headers” option takes a Header object. This object allows you to configure the headers you want to add to your request. By adding pragma: no-cache and a cache-control: no-cache to your header you will force the browser to check the server to …
https://stackoverflow.com/questions/29246444/fetch-how-do-you-make-a-non-cached-request