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Reflect & Proxy Reference


Complete Reflect Reference

Revised December 2025

MethodDescription
Reflect.apply() Call a function
Reflect.construct() Create object (like new)
Reflect.defineProperty() Define a property
Reflect.deleteProperty() Delete a property
Reflect.get() Get a property
Reflect.getOwnPropertyDescriptor() Get property descriptor
Reflect.getPrototypeOf() Get the prototype of an object
Reflect.has() Check if property exists
Reflect.isExtensible() Check if object can grow
Reflect.ownKeys() Get all keys (incl. symbols)
Reflect.preventExtensions() Stop object from growing
Reflect.set() Set a property
Reflect.setPrototypeOf() Set the prototype of an object

Why Reflect

Reflect is safe and flexible, especially when used inside a Proxy.

Complete Proxy Handler Reference

Revised December 2025

MethodDescription
handler.apply() Call a function
handler.construct() Create object (like new)
handler.defineProperty() Define a property
handler.deleteProperty() Delete a property
handler.get() Get a property
handler.getOwnPropertyDescriptor() Get property descriptor
handler.getPrototypeOf() Get the prototype of an object
handler.has() Check if property exists
handler.isExtensible() Check if object can grow
handler.ownKeys() Get all keys (incl. symbols)
handler.preventExtensions() Stop object from growing
handler.set() Set a property
handler.setPrototypeOf() Set the prototype of an object

JavaScript Internal Methods

All JavaScript objects have 13 internal methods.

Each method has a corresponding Proxy trap:

Internal Operation Proxy trap
[[Construct]]construct()
[[Call]]apply()
[[Get]]get()
[[Set]]set()
[[HasProperty]]has()
[[Delete]]deleteProperty()
[[DefineProperty]]defineProperty()
[[GetOwnProperty]]getOwnProperty()
[[OwnPropertyKeys]]ownPropertyKeys()
[[IsExstensible]]isExtensible()
[[PreventExstensions]]preventExtensions()
[[GetPrototypeOf]]getPrototypeOf()
[[SetPrototypeOf]]setPrototypeOf()

Note

Every Proxy trap has a Reflect method with the same name and signature.

Internal Operation Reflect Method
[[Construct]]Reflect.construct()
[[Call]]Reflect.apply()
[[Get]]Reflect.get()
[[Set]]Reflect.set()
[[HasProperty]]Reflect.has()
[[Delete]]Reflect.deleteProperty()
[[DefineProperty]]Reflect.defineProperty()
[[GetOwnProperty]]Reflect.getOwnProperty()
[[OwnPropertyKeys]]Reflect.ownPropertyKeys()
[[IsExstensible]]Reflect.isExtensible()
[[PreventExstensions]]Reflect.preventExtensions()
[[GetPrototypeOf]]Reflect.getPrototypeOf()
[[SetPrototypeOf]]Reflect.setPrototypeOf()


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