JavaScript Proxy and Reflect Metaprogramming Quiz

Review

1. What does new Proxy(target, handler) create?

   It creates a Proxy whose target and handler control intercepted internal operations.
2. Which trap intercepts property reads?

   get corresponds to the proxy [[Get]] operation.
3. Which operation is the usual forwarding primitive inside a set trap?

   Reflect.set delegates the standard [[Set]] operation.
4. Which syntax uses the has trap?

   The in operator uses the property-existence operation represented by the has trap.
5. Which Reflect operation retrieves all own keys including symbols?

   Reflect.ownKeys exposes the full own-key operation.
6. What can an invariant violation by a trap cause?

   The proxy internal methods enforce invariants and can throw TypeError.
7. What happens when a handler lacks a trap?

   Missing traps use the target operation.
8. What does Proxy.revocable provide?

   Proxy.revocable returns { proxy, revoke }.
9. Which trap intercepts calls to a callable proxy?

   apply corresponds to the proxy [[Call]] operation.
10. Why use Reflect inside a trap?

    Reflect provides explicit forwarding operations; it does not bypass invariants.