Disable nginx cache for JavaScript files

The expires and add_header directives have no impact on NGINX caching the files, those are purely about what the browser sees.

What you likely want instead is:

location stuffyoudontwanttocache {
    # don't cache it
    proxy_no_cache 1;
    # even if cached, don't try to use it
    proxy_cache_bypass 1; 
}

Though usually .js etc is the thing you would cache, so perhaps you should just disable caching entirely?

What you are looking for is a simple directive like:

location ~* \.(?:manifest|appcache|html?|xml|json)$ {
    expires -1;
}

The above will not cache the extensions within the (). You can configure different directives for different file types.

I have the following nginx virtual host (static content) for local development work to disable all browser caching:

server {
    listen 8080;
    server_name localhost;

    location / {
        root /your/site/public;
        index index.html;

        # kill cache
        add_header Last-Modified $date_gmt;
        add_header Cache-Control 'no-store, no-cache';
        if_modified_since off;
        expires off;
        etag off;
    }
}

No cache headers sent:

$ curl -I http://localhost:8080
HTTP/1.1 200 OK
Server: nginx/1.12.1
Date: Mon, 24 Jul 2017 16:19:30 GMT
Content-Type: text/html
Content-Length: 2076
Connection: keep-alive
Last-Modified: Monday, 24-Jul-2017 16:19:30 GMT
Cache-Control: no-store
Accept-Ranges: bytes

Last-Modified is always current time.

Note: nginx's $date_gmt format is not per the HTTP spec (see changing the format).