Proxy and ReflectBaseline · Widely available

The Proxy and Reflect JavaScript built-ins intercept and define custom behavior for fundamental language operations (such as property lookup, assignment, enumeration, or function invocation).

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Sep 20, 2016. Widely available since Mar 20, 2019.

How to use ↓Compare browsers

Browser support

DesktopChrome

1–48Not supported

49+Supportedsince Mar 2, 2016

Current: 155

Edge

12+Supportedsince Jul 29, 2015

Current: 154

Firefox

1–17Not supported

18+Supportedsince Jan 8, 2013

Current: 157

Safari

1–9.1Not supported

10+Supportedsince Sep 20, 2016

Current: 27

MobileChrome Android

18–48Not supported

49+Supportedsince Mar 9, 2016

Current: 155

Firefox Android

4–17Not supported

18+Supportedsince Jan 8, 2013

Current: 157

Safari iOS

1–9.3Not supported

10+Supportedsince Sep 13, 2016

Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN: Proxy.

Feature detection

JS · check before using

if (typeof Proxy !== "undefined") {
  // Proxy is available
}

Documentation (MDN)

Specification

tc39.es#sec-reflection ↗

Usage share

caniuse.com/proxy ↗

Sub-features

Support for each part of the feature (30). The overall table above shows when the whole feature works.

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
Proxy	49	12	18	10	49	18	10
Proxy.Proxy	49	12	18	10	49	18	10
Proxy.handler.apply	49	12	18	10	49	18	10
Proxy.handler.construct	49	12	18	10	49	18	10
Proxy.handler.defineProperty	49	12	18	10	49	18	10
Proxy.handler.deleteProperty	49	12	18	10	49	18	10
Proxy.handler.get	49	12	18	10	49	18	10
Proxy.handler.getOwnPropertyDescriptor	49	12	18	10	49	18	10
Proxy.handler.getPrototypeOf	49	79	49	10	49	49	10
Proxy.handler.has	49	12	18	10	49	18	10
Proxy.handler.isExtensible	49	12	31	10	49	31	10
Proxy.handler.ownKeys	49	12	18	10	49	18	10
Proxy.handler.preventExtensions	49	12	22	10	49	22	10
Proxy.handler.set	49	12	18	10	49	18	10
Proxy.handler.setPrototypeOf	49	12	49	10	49	49	10
Proxy.revocable	63	12	34	10	63	34	10
Reflect	49	12	42	10	49	42	10
Reflect.apply	49	12	42	10	49	42	10
Reflect.construct	49	12	42	10	49	42	10
Reflect.defineProperty	49	12	42	10	49	42	10

Show 10 more

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
Reflect.deleteProperty	49	12	42	10	49	42	10
Reflect.get	49	12	42	10	49	42	10
Reflect.getOwnPropertyDescriptor	49	12	42	10	49	42	10
Reflect.getPrototypeOf	49	12	42	10	49	42	10
Reflect.has	49	12	42	10	49	42	10
Reflect.isExtensible	49	12	42	10	49	42	10
Reflect.ownKeys	49	12	42	10	49	42	10
Reflect.preventExtensions	49	12	42	10	49	42	10
Reflect.set	49	12	42	10	49	42	10
Reflect.setPrototypeOf	49	12	42	10	49	42	10