const targetObject = name: "Proxy Example", version: 2021 ; const handler = get(target, prop, receiver) console.log( GET $String(prop) ); return Reflect.get(target, prop, receiver); , set(target, prop, value, receiver) console.log( SET $String(prop) = $value ); return Reflect.set(target, prop, value, receiver); , has(target, prop) console.log( Checking existence of $String(prop) ); return Reflect.has(target, prop); , deleteProperty(target, prop) console.log( Deleting $String(prop) ); return Reflect.deleteProperty(target, prop);
const handler = get(target, prop, receiver) if (prop in target) return target[prop]; else return "Default Value"; ; This works, but it is fragile. It doesn't properly handle inheritance, getters, or the receiver binding. The Reflect API, introduced in ES6 (ES2015) but fully matured by 2021, provides a set of methods for interceptable JavaScript operations. The key insight is that every method on Reflect has a matching counterpart in the Proxy handler . proxy made with reflect 4 2021
const proxyMadeWithReflect = new Proxy(targetObject, handler); const targetObject = name: "Proxy Example", version: 2021
;
In the ever-evolving landscape of JavaScript, certain patterns and syntax updates stand out as game-changers for developers. One such powerful combination that gained significant traction in 2021 was the synergy between the Proxy object and the Reflect API. The key insight is that every method on
// A complete proxy with Reflect (the "Reflect 4" pattern) function createAuditProxy(subject, name = "Object") const handler = get(target, prop, receiver) console.log(`[$name] GET $String(prop)`); return Reflect.get(target, prop, receiver); , set(target, prop, value, receiver) console.log(`[$name] SET $String(prop) = $JSON.stringify(value)`); return Reflect.set(target, prop, value, receiver); , has(target, prop) const exists = Reflect.has(target, prop); console.log(`[$name] HAS $String(prop)? $exists`); return exists; , deleteProperty(target, prop) console.log(`[$name] DELETE $String(prop)`); return Reflect.deleteProperty(target, prop); ; return new Proxy(subject, handler);