Proxy handler

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  1. Methods
  2. Specifications
  3. Browser compatibility
  4. See also

The proxy's handler object is a placeholder object which contains traps for proxies.

Methods

All traps are optional. If a trap has not been defined, the default behavior is to forward the operation to the target.

handler.getPrototypeOf()
A trap for Object.getPrototypeOf.
handler.setPrototypeOf()
A trap for Object.setPrototypeOf.
handler.isExtensible()
A trap for Object.isExtensible.
handler.preventExtensions()
A trap for Object.preventExtensions.
handler.getOwnPropertyDescriptor()
A trap for Object.getOwnPropertyDescriptor.
handler.defineProperty()
A trap for Object.defineProperty.
handler.has()
A trap for the in operator.
handler.get()
A trap for getting property values.
handler.set()
A trap for setting property values.
handler.deleteProperty()
A trap for the delete operator.
handler.ownKeys()
A trap for Object.getOwnPropertyNames and Object.getOwnPropertySymbols.
handler.apply()
A trap for a function call.
handler.construct()
A trap for the new operator.

Some non-standard traps are obsolete and have been removed.

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Proxy Object Internal Methods and Internal Slots' in that specification.		 Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Proxy Object Internal Methods and Internal Slots' in that specification.		 Draft The enumerate handler has been removed.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
applyChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
constructChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
definePropertyChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
deletePropertyChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
enumerate
DeprecatedNon-standard
Chrome No support NoEdge No support NoFirefox No support 37 — 47IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android No support 37 — 47Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support Nonodejs No support No
getChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
getOwnPropertyDescriptorChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
getPrototypeOfChrome Full support 49Edge No support NoFirefox Full support 49IE No support NoOpera Full support 36Safari No support NoWebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 49Opera Android Full support 36Safari iOS No support NoSamsung Internet Android Full support Yesnodejs Full support 6.0.0
hasChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
isExtensibleChrome ? Edge ? Firefox Full support 31IE No support NoOpera ? Safari ? WebView Android ? Chrome Android ? Firefox Android Full support 31Opera Android ? Safari iOS ? Samsung Internet Android ? nodejs Full support 6.0.0
ownKeysChrome Full support 49Edge Full support 12Firefox Full support 18
Notes
Full support 18
Notes
Notes In Firefox 42, the implementation got updated to reflect the final ES2015 specification: The result is now checked if it is an array and if the array elements are either of type string or of type symbol. Enumerating duplicate own property names is not a failure anymore.
IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18
Notes
Full support 18
Notes
Notes In Firefox 42, the implementation got updated to reflect the final ES2015 specification: The result is now checked if it is an array and if the array elements are either of type string or of type symbol. Enumerating duplicate own property names is not a failure anymore.
Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
preventExtensionsChrome Full support 49Edge Full support 12Firefox Full support 22IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 22Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
setChrome Full support 49Edge Full support 12Firefox Full support 18IE No support NoOpera Full support 36Safari Full support 10WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 18Opera Android Full support 36Safari iOS Full support 10Samsung Internet Android Full support 5.0nodejs Full support 6.0.0
setPrototypeOfChrome Full support 49Edge ? Firefox Full support 49IE No support NoOpera Full support 36Safari ? WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 49Opera Android Full support 36Safari iOS ? Samsung Internet Android Full support Yesnodejs Full support 6.0.0

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
Deprecated. Not for use in new websites.
Deprecated. Not for use in new websites.
See implementation notes.
See implementation notes.

See also

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Contributors to this page: mdnwebdocs-bot, fscholz, SphinxKnight, fasttime, kdex, jwhitlock, DanielHerr, pnevyk, ziyunfei, arai
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