JSFiddle - React, Tailwind, and code Playground

JavaScript

(function() {
    'use strict';
    
    class CSampleClass {
      constructor(value1, value2) {
        if ( new.target == CSampleClass ) {
       		this.privateVar = "is here"; //this wont be inherited
        }

        this.v1 = value1;
        this.v2 = value2;
      }
    }

    class CSampleClassChild extends CSampleClass {
        constructor(value1, value2) {
            super(value1, value2);
        }
    }
    
    var test = new CSampleClass(1,2);
    var test2 = new CSampleClassChild(1,2);
    
    console.log("privateVar from object(CSampleClass):", test.privateVar);
    console.log("privateVar from object(CSampleClassChild):", test2.privateVar);
})();