How can I define a default getter and setter using ECMAScript 5?

Question

How can I specify a default getter for a prototype? With default getter I mean a function that is called if obj.undefinedProperty123 is called.

I tried

Answer 1

You want to create a Proxy:

const data = {};

const proxy = new Proxy(data, {
  get: (target, prop) => {
    console.log({ target, prop });
    return "My Value";
  },
  set: (target, prop, value) => {
    console.log({ target, prop, value });
    return true;
  },
});

proxy["foo"] = "bar";
const bar = proxy["foo"];