JSFiddle - React, Tailwind, and code Playground

JavaScript

function A() {}
A.prototype._Adata = [];

A.prototype.add = function(rec) {
  this._Adata.push(rec);
};

A.prototype.get = function() {
  return this._Adata;
};

function B() {}
B.prototype = Object.create(A.prototype, { constructor: { value: B }});

B.prototype._Bdata = [];

B.prototype.add = function(rec) {
  this._Bdata.push(rec);
};
B.prototype.get = function() {
  return this._Adata.concat(this._Bdata);
};

var a = new A();
var b = new B();

a.add('aa');
b.add('bb');
console.log(b.get()); // [aa, bb]

a.add('aaaa');
console.log(b.get()); // [aa, aaaa, bb]