recursive-object-proxy.js

const handler = {
  get (obj, prop) {
    if (prop in obj) {
      if (typeof obj[prop] === 'object') {
        return new Proxy(obj[prop], handler)
      }
      return obj[prop]
    }
    return new Proxy({}, handler)
  }
}

const p = new Proxy({a: {b: {c: 1}}}, handler)

console.log(p.a.d, p.b, p.a.b.f, p.a.b.c, p.b.c.a)