title: get class instance from require()
body: <p>Say I have a normal module</p>
  
  <pre><code>  module.exports = class MyClass{ }
  </code></pre>
  
  <p>The standard way to use it is like this:</p>
  
  <pre><code>const MyClass = require('myclass.js');
  </code></pre>
  
  <p>But what if I don't know the class name and the file name is a variable? How do I get the class from it?</p>
  
  <pre><code>const ???? = require(file + '.js');
  </code></pre>