The handler.get()
method is a trap for getting a property value.
handler.get()
Try it
Syntax
new Proxy(target, { get: function(target, property, receiver) { } });
Parameters
The following parameters are passed to the get()
method. this
is bound to the handler.
-
target
-
The target object.
-
property
-
The name or
Symbol
of the property to get. -
receiver
-
Either the proxy or an object that inherits from the proxy.
Return value
The get()
method can return any value.
Description
The handler.get()
method is a trap for getting a property value.
Interceptions
This trap can intercept these operations:
- Property access:
proxy[foo]
andproxy.bar
- Inherited property access:
Object.create(proxy)[foo]
Reflect.get()
Invariants
If the following invariants are violated, the proxy will throw a TypeError
:
- The value reported for a property must be the same as the value of the corresponding target object property if the target object property is a non-writable, non-configurable own data property.
- The value reported for a property must be undefined if the corresponding target object property is a non-configurable own accessor property that has
undefined
as its[[Get]]
attribute.
Examples
Trap for getting a property value
The following code traps getting a property value.
const p = new Proxy({}, { get: function(target, property, receiver) { console.log('called: ' + property); return 10; } }); console.log(p.a); // "called: a" // 10
The following code violates an invariant.
const obj = {}; Object.defineProperty(obj, 'a', { configurable: false, enumerable: false, value: 10, writable: false }); const p = new Proxy(obj, { get: function(target, property) { return 20; } }); p.a; // TypeError is thrown
Specifications
Specification |
---|
ECMAScript Language Specification # sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver |
Browser compatibility
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
get |
49
|
12
|
18
|
No
|
36
|
10
|
49
|
49
|
18
|
36
|
10
|
5.0
|
1.0
|
6.0.0
|
See also
© 2005–2022 MDN 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/Proxy/get