proxy-pattern

Create a new Proxy with the target object and a handler defining get and set traps. The get trap runs on property reads and the set trap runs on writes, letting you log, validate, or transform values before they reach the target.

Use a Proxy set trap to check values before assignment, such as rejecting non-numeric ages or names shorter than two characters. Return true for valid writes and skip the assignment or throw for invalid ones.

Proxy intercepts all operations through a handler object and works on any property, including ones added later. Object.defineProperty defines getters and setters per property with less indirection, which suits simple validation on known keys.

Reflect.get and Reflect.set mirror the handler trap signatures and forward operations to the target with correct receiver binding. This avoids subtle bugs from direct bracket access, especially with inherited properties or accessor descriptors.

Avoid Proxy in performance-critical hot paths because every property access incurs trap overhead. Also skip it when simple getters, setters, or plain functions achieve the same validation with less indirection.