title: Gatsby JS files expiry headers
body: <p>I am trying to get my head around expiry headers for JS files generated by Gatsby JS. There is an article about caching on the official website: <a href="https://www.gatsbyjs.org/docs/caching/" rel="nofollow noreferrer">https://www.gatsbyjs.org/docs/caching/</a>. Author suggests to use <code>cache-control: public, max-age=0, must-revalidate</code> header for JS files.</p>
  
  <p>I would like to cache all JS resources. What are possible implications of usage of <code>cache-control: max-age=31536000, public</code>? Currently, I am using <code>1.9.192</code> version and JS file hashes are anyway different on each build.</p>
  
  <p>By the way, there is a <code>gatsby-plugin-offline</code> which allows to cache JS resources using service worker. What could a reason why I should not use long term browser cache then?</p>