title: How to clean node_modules folder of packages that are not in package.json?
body: <p>Assume I install project packages with <code>npm install</code> that looks into <code>package.json</code> for modules to be installed. After a while I see that I don't need some specific module and remove its dependency from <code>package.json</code>. Then I remove some other modules from <code>package.json</code> because they are not needed anymore and others are replaced with alternatives. </p>
  
  <p>Now I want to clean <code>node_modules</code> folder so that only modules listed in <code>package.json</code> stay there and the rest must go, something like <code>npm clean</code>. I know I can remove them manually but would like to have some nice ready to use sugar functionality for that.</p>