;
The primary use case for a Reflect 4 proxy is
const target = name: "target" ; const proxy = new Proxy(target, set(trapTarget, key, value, receiver) if (!trapTarget.hasOwnProperty(key) && isNaN(value)) throw new TypeError("Property must be a number"); proxy made with reflect 4 2021
); ;
The core question for many developers is: why is it mandatory to pair Proxy with Reflect for a pure forwarding proxy? The answer lies in preserving the complete integrity of the object's original behavior. Directly manipulating the target object (e.g., target[prop] = value ) instead of using Reflect can introduce subtle bugs: ; The primary use case for a Reflect
;
Whether you need to support within the traps Every operation that passes through a Proxy introduces
While Proxies and Reflect are powerful, they are not free. Every operation that passes through a Proxy introduces a small overhead, and using many traps can become noticeable in performance‑critical code. In 2021, modern JavaScript engines had already optimised Proxies significantly, but they are still slower than direct object access.
When you use Reflect inside a Proxy trap, you ensure that the default behavior of the operation is preserved. Without it, you often break the internal "this" binding of the object or fail to return the boolean values that certain operations expect. Anatomy of a Proxy with Reflect
: Released during the transition to Apple Silicon, Reflector 4 was optimized to run natively on the