how to get fetch response header in js
https://stackoverflow.com/questions/43344819/reading-response-headers-with-fetch-api
how to get ajax response header in js
https://www.yukei.net/2016/01/getting-response-headers-data-from-an-ajax-request-with-jquery/
https://stackoverflow.com/questions/1557602/jquery-and-ajax-response-header
xhr.getResponseHeader('Header')