Example Nginx configuration for serving pre-rendered HTML from Javascript pages/apps using the Prerender Service (https://github.com/collectiveip/prerender). Instead of using try_files (which can cause unnecessary overhead on busy servers), you could check $uri for specific file extensions and set $prerender appropriately.

nginx.conf

server {
    listen 80;
    listen [::]:80;
    server_name yourserver.com;

    root /path/to/your/htdocs;

    error_page 404 /404.html
    index index.html;

    location ~ /\. {
        deny all;
    }

    location / {
        try_files $uri @prerender;
    }

    location @prerender {
        #proxy_set_header X-Prerender-Token YOUR_TOKEN;

        set $prerender 0;
        if ($http_user_agent ~* "googlebot|yahoo|bingbot|baiduspider|yandex|yeti|yodaobot|gigabot|ia_archiver|facebookexternalhit|twitterbot|developers\.google\.com") {
            set $prerender 1;
        }
        if ($args ~ "_escaped_fragment_|prerender=1") {
            set $prerender 1;
        }
        if ($http_user_agent ~ "Prerender") {
            set $prerender 0;
        }

        if ($prerender = 1) {
            rewrite .* /$scheme://$host$request_uri? break;
            #proxy_pass http://localhost:3000;
            proxy_pass http://service.prerender.io;
        }
        if ($prerender = 0) {
            rewrite .* /index.html break;
        }
    }
}