Start refactoring your proxies today—replace manual logic with Reflect and watch your code become more reliable, elegant, and performant. Further Reading: MDN Web Docs – Proxy & Reflect, TC39 Proposal Details, "Metaprogramming in JavaScript" by Keith Kirk. Have a specific use case? Drop a comment below.
: It uses Reflect to capture the exact value, including getters that might compute results dynamically. 3. Validation Proxy (Top Security) A common requirement is to validate data before allowing mutations. This pattern powers libraries like Vuex and MobX. proxy made with reflect 4 top
function createTransparentProxy(target) { return new Proxy(target, { get(target, prop, receiver) { return Reflect.get(target, prop, receiver); }, set(target, prop, value, receiver) { return Reflect.set(target, prop, value, receiver); }, has(target, prop) { return Reflect.has(target, prop); }, deleteProperty(target, prop) { return Reflect.deleteProperty(target, prop); }, apply(target, thisArg, argumentsList) { return Reflect.apply(target, thisArg, argumentsList); }, construct(target, argumentsList, newTarget) { return Reflect.construct(target, argumentsList, newTarget); } }); } Using Reflect ensures that if the target object has native getters or inherits from a prototype, the proxy respects those behaviors without additional code. One of the "top" use cases is logging without breaking the application logic. Drop a comment below
By using Reflect.set , you ensure that if the property is read-only or non-configurable, the proxy correctly returns false instead of throwing an inconsistent error. For expensive operations like API calls or database queries, a "top" pattern is caching and retry logic. Validation Proxy (Top Security) A common requirement is
function createValidationProxy(target, validator) { return new Proxy(target, { set(target, prop, value, receiver) { if (validator[prop] && !validator[prop](value)) { throw new TypeError(`Invalid value for ${String(prop)}: ${value}`); } return Reflect.set(target, prop, value, receiver); } }); } const person = { age: 25 }; const ageValidator = { age: (val) => typeof val === 'number' && val >= 0 && val <= 120 };
This pattern is used in ORMs and cloud SDKs to delay resource allocation until the first property access. Even with Reflect , pitfalls remain. Here’s how to avoid them: Pitfall 1: Forgetting the Receiver Argument The receiver in traps like get and set is the proxy itself (or an object inheriting from it). Always pass it to Reflect .
