AI solution for JavaScript Quiz on BFE.dev
48. Prototype

The code outputs:

1 2 2 2 2 3

Explanation:

• We create a new function Foo, then add a property bar to its prototype with a value of 1.
• We create a new instance of Foo with const a = new Foo(). This instance has bar property inherited from Foo.prototype, which is equal to 1. We log a.bar to the console and get 1.
• We change the value of bar property on Foo.prototype to 2. Since a was created before that change, its bar property is still equal to 1. However, when we create a new instance of Foo with const b = new Foo(), its bar property is equal to 2. We log a.bar and get 1, and b.bar and get 2.
• We completely redefine Foo.prototype with an object that has a bar property equal to 3. This change does not affect a or b, since they still have their own internal prototype chains with the old Foo.prototype. However, a new instance of Foo created after this change, const c = new Foo(), does inherit from the new prototype object with bar property equal to 3. We log a.bar and get 1, b.bar and get 2, and c.bar and get 3.