title: Should use Class or Module in NodeJS
body: <p>I'm newbie on NodeJS. I'm researching about the inheritance on NodeJS and found there's an inheritance using Class (on ES6). I have some questions about the using of the Class and Module to decide which one should be used in my case:</p>
  
  <ol>
  <li>As I know, "<code>Module</code>" is cached after i run once, it means I don't need to initial every time, and for "Class" which i need to initial every time I use it. So does it make a leak memory or not good for performance?</li>
  <li>In my case, i would like to implement the inheritance for some common functions, then i can reuse them in my child. In case using "<code>Class</code>": If there are multiple request sent from Client side at the same time, does it affect to the Server's performance  such as the slower's response or anything? </li>
  <li>If using "<code>CLASS</code>", can I trigger ONCE for a global function( Any other inheritance classes will not trigger that function.)</li>
  <li>After create an instance of Class and processing the functionality, will it be released?</li>
  </ol>
  
  <p>Thanks in advance.</p>