JSFiddle - React, Tailwind, and code Playground

JavaScript

var box = {
  locked: true,
  unlock: function() { this.locked = false; },
  lock: function() { this.locked = true;  },
  _content: ['hello', 'world'],
  get content() {
    if (this.locked) throw new Error("Заперто!");
    return this._content;
  }
};

box.unlock()
console.log(box.content)