How to set expiration date for static files being served directly by Nginx

map $sent_http_content_type $expires {
    default    off;

    # Images expires in 2 weeks
    image/png 2w;
    image/gif 2w;
    image/jpg 2w;
    image/jpeg 2w;
    image/ico 2w;
    image/x-icon 2w;
    image/vnd.microsoft.icon 2w;
    image/svg+xml 2w;
    application/x-font-woff 2w;

    # CSS/JS now work with dynamic unique query string. 1 year expires
    text/css 1y;
    text/javascript 1y;
    application/javascript 1y;
}