title: What's the difference between --dev, --save, and --save-dev for npm?
body: <p>My understanding is this:</p>
  
  <pre><code>npm install //Installs everything that is listed in package.json
  npm install --production //install everything minus dev packages
  npm install $package --save //installs and add it to package.json
  npm install $package --dev //install and add it to package.json but under dev
  npm install --save-dev //??? isn't same thing as --dev flag
  </code></pre>
  
  <p>maybe there is no such thing as</p>
  
  <pre><code>npm install $package --dev
  </code></pre>