Get the directory of a subclass from the parent class in NodeJS.

MySuperClass.js

const path = require('path');

// this is the key function where all the magic happens
function getSubclassDir() {
  // override prepareStackTrace
  // error.stack will be <CallSite>[] rather than <string>
  const original = Error.prepareStackTrace;
  Error.prepareStackTrace = function(err, stack) { return stack; };
  
  // create a new error and use the stack
  // crawl up the stack until we reach another module
  // that will be the one that called us - which will be the subclass
  var err = new Error();
  var current = err.stack.shift().getFileName(), callingModule = current;
  while(err.stack.length > 0 && callingModule == current)
    callingModule = err.stack.shift().getFileName();
    
  // put original function back
  Error.prepareStackTrace = original;
  
  // return the directory
  return path.dirname(callingModule);
}

// superclass sets homeDir - will always be the directory the subclass resides in
module.exports = class MySuperClass {
  constructor() {
    // check if this is subclass...
    if(this.constructor.name != 'MySuperClass')
      this.homeDir = getSubclassDir();
    else this.homeDir == __dirname;
  }
};