I solved putting :

location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
try_files $uri $uri/ =404;


#if ($http_origin = ''){
#set $http_origin "*";
#}
#proxy_hide_header Access-Control-Allow-Origin;
#add_header Access-Control-Allow-Origin $http_origin;

autoindex on;
autoindex_exact_size off;
autoindex_localtime on;

add_header 'Access-Control-Allow-Origin' "$http_origin" always;
add_header 'Access-Control-Allow-Credentials' 'true' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,Range,User-Agent,X-Requested-With' always;

if ($request_method = 'OPTIONS') {
# Tell client that this pre-flight info is valid for 20 days
add_header 'Access-Control-Allow-Origin' "$http_origin" always;
add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,Range,User-Agent,X-Requested-With' always;
add_header 'Access-Control-Max-Age' 1728000;
add_header 'Content-Type' 'text/plain charset=UTF-8';
add_header 'Content-Length' 0;
return 204;
}



}