virtual-proxy

VirtualProxy

The Proxy API enables powerful reflection on JavaScript objects. However, it is constrained by strict invariants, such as requiring proxies to report consistent values for immutable properties (i.e., non-configurable and non-writable). While these invariants are essential for ensuring the consistent behavior of JavaScript objects, the current implementation imposes unnecessary limitations by using the target object for bookkeeping.

This module introduces a mechanism to decouple the target object from the bookkeeping process, enabling more flexible and versatile use of proxies.

Demo

import { VirtualProxy, setupVirtualHandler } from "../lib/index.mjs";
const target = Object.freeze({
  name: "John",
  password: "1234",
});
const handler = {
  get: (target, key, receiver) =>
    key === "password" ? "****" : Reflect.get(target, key, receiver),
};
// 1) Proxy
{
  // TypeError: 'get' on proxy: property 'password' is a read-only and
  // non-configurable data property on the proxy target but the proxy
  // did not return its actual value
  const proxy = new Proxy(target, handler);
  console.log(proxy.password);
}
// 2) VirtualProxy
{
  const integrity = {};
  const proxy = new VirtualProxy(integrity, target, handler);
  console.log(proxy.password); // ****
}
// 3) setupVirtualHandler
{
  const integrity = {};
  const proxy = new Proxy(integrity, setupVirtualHandler(target, handler));
  console.log(proxy.password); // ****
}

API

TypeScript Declaration