A test case for a module-like pattern for inheritance using Object.create(). Useful in older JS versions, requiring just a shim for Object.create().

modular_inheritance.js

Parent.count = 0;

function Parent(val) {

	var value = val;
  var index = -1;

	(function constructor(c) {
			index = c;
		})(Parent.count++);

  function toString() {
    return value + ":" + index;
  }

	var publicInterface = Object.create({},{
  		inheritedProp: { value: index },
	  	toString: { value: toString }
    });
    
  return publicInterface;
}


function Child(val) {

	var sup = new Parent(val);

  function toString() {
    return sup.toString() + " overridden";
  }

	var publicInterface = Object.create(sup,{
  	toString: { value: toString },
  	doSomething: { value: function() { console.log("something"); } }
  });

  return publicInterface;
}

const bar = new Parent("bar");
const baz = new Child("baz");

console.log("bar: ",bar.toString(), bar.inheritedProp, bar);
console.log("baz: ",baz.toString(), baz.inheritedProp, baz);
console.log(bar.toString === baz.toString);
baz.doSomething();