JSFiddle - React, Tailwind, and code Playground

JavaScript

function A() {}
         A.prototype._data = [];
    
     A.prototype.add = function(rec) {
       this._data.push(rec);
     }
    
     A.prototype.get = function() {
       return this._data;
     }
    
     function B() {}
     B.prototype = Object.create(A.prototype, { constructor: { value: B    }});
     
     B.prototype._data = [];

     B.prototype.get = function() {
       return A.prototype._data.concat(this._data);
     }  
     
     var a = new A(), 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]