A Nginx conf for handling OPTIONS request for functions like window.fetch

nginx-options-request.conf

server {

    # ...

    # handle OPTIONS requests from window.fetch
    if ($request_method = OPTIONS ) {
        add_header Access-Control-Allow-Origin "*";
        add_header Access-Control-Allow-Methods "GET, OPTIONS";
        add_header Access-Control-Allow-Headers "Authorization,content-type";
        add_header Access-Control-Allow-Credentials "true";
        add_header Content-Length 0;
        add_header Content-Type text/plain;
        return 200;
    }

    # ...

}

This will not work. Because IF is evil and it only allowed inside of location