title: How to instruct `npm` to not download existing packages?
body: <p>Although it should be the responsibility of <code>npm</code> cli tool itself but since the logs indicate that it contacts the npm registry even for packages that are already present ... my question becomes:</p>
  
  <blockquote>
    <p>How do we avoid contacting npm registry for any packages that are already present in <code>node_modules</code> folder?</p>
  </blockquote>
  
  <p>While I understand that it is part of the <code>npm</code> algorithm to create a complete clone by downloading all dependencies and then comparing them with the existing ones, it is way too inefficient for CI builds and I'm seeking advice or pointers to scritps that handle this better.</p>