const cookieDescriptor = Object.getOwnPropertyDescriptor(Document.prototype, 'cookie') || Object.getOwnPropertyDescriptor(HTMLDocument.prototype, 'cookie');

Object.defineProperty(document, 'cookie', {
    get: function() {
          return cookieDescriptor.get.call(document);
    },
    set: function(cookieString) {
          const cookieName = cookieString.split('=')[0].trim();

          if (nem követő kuki){
                cookieDescriptor.set.call(document, cookieString);
          }
    },
    configurable: false,
    enumerable: true
});