Proxy.revocable()
The Proxy.revocable()
method is used to create a revocable Proxy
object.
Syntax
JavaScript
Copy Code
Proxy.revocable(target, handler);
Parameters
target
- A target object (can be any sort of objects, including a native array, a function or even another proxy) or function to wrap with
Proxy
. handler
- An object whose properties are functions which define the behavior of the proxy when an operation is performed on it.
Return value
A newly created revocable Proxy
object is returned.
Description
A revocable Proxy
is an object with following two properties {proxy: proxy, revoke: revoke}
.
proxy
- A Proxy object created with
new Proxy(target, handler)
call. revoke
- A function with no argument to invalidate (switch off) the
proxy
.
If the revoke()
function gets called, the proxy becomes unusable: Any trap to a handler will throw a TypeError
. Once a proxy is revoked, it will remain revoked and can be garbage collected. Calling revoke()
again has no effect.
Examples
JavaScript
Copy Code
var revocable = Proxy.revocable({}, { get: function(target, name) { return "[[" + name + "]]"; } }); var proxy = revocable.proxy; console.log(proxy.foo); // "[[foo]]" revocable.revoke(); console.log(proxy.foo); // TypeError is thrown proxy.foo = 1 // TypeError again delete proxy.foo; // still TypeError typeof proxy // "object", typeof doesn't trigger any trap
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Proxy Revocation Functions' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Proxy Revocation Functions' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | 34 (34) | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 34 (34) | No support | No support | No support |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/proxy/revocable