title: Does express.static() cache files in the memory?
body: <p>In ExpressJS for NodeJS, we can do the following:</p>
  
  <pre><code>app.use(express.static(__dirname + '/public'));
  </code></pre>
  
  <p>to serve all the static CSS, JS, and image files. My questions are these:</p>
  
  <p>1) When we do that, does Express automatically cache the files in the server's memory or does it read from the hard disk every time one of the resources is served?</p>
  
  <p>2) When we do that, does Express, using ETag by default, save the resources on the client's hard disk, or on the client's memory only?</p>