title: How can I make express do checksum-based caching?
body: <p>I'm aware of Express' <code>maxAge</code> directive for static content:</p>
  
  <pre><code>app.use(express.static(__dirname + '/public', { maxAge: 86400000 }));
  </code></pre>
  
  <p>However I'd like to set up a system where:</p>
  
  <ul>
  <li>Browsers cache any resource that has not changed</li>
  <li>Browsers fetch the latest version of resources that have changed</li>
  </ul>
  
  <p>I understand this is normally done with checksums, ie: <strong>serve all resources with a checksum as part of their URL</strong>. Old URLs are cached forever, new content means new URLs.</p>
  
  <p><strong>How can I set this up in express?</strong></p>