The static Reflect.isExtensible()
method determines if an object is extensible (whether it can have new properties added to it). It is similar to Object.isExtensible()
, but with some differences.
Reflect.isExtensible()
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Syntax
Reflect.isExtensible(target)
Parameters
-
target
-
The target object which to check if it is extensible.
Return value
A Boolean
indicating whether or not the target is extensible.
Exceptions
Description
The Reflect.isExtensible
method allows you determine if an object is extensible (whether it can have new properties added to it). It is the same method as Object.isExtensible()
.
Examples
Using Reflect.isExtensible()
See also Object.isExtensible()
.
// New objects are extensible. let empty = {} Reflect.isExtensible(empty) // === true // ...but that can be changed. Reflect.preventExtensions(empty) Reflect.isExtensible(empty) // === false // Sealed objects are by definition non-extensible. let sealed = Object.seal({}) Reflect.isExtensible(sealed) // === false // Frozen objects are also by definition non-extensible. let frozen = Object.freeze({}) Reflect.isExtensible(frozen) // === false
Difference to Object.isExtensible()
If the target
argument to this method is not an object (a primitive), then it will cause a TypeError
. With Object.isExtensible()
, a non-object first argument will be coerced to an object at first.
Reflect.isExtensible(1) // TypeError: 1 is not an object Object.isExtensible(1) // false
Specifications
Browser compatibility
Desktop | Mobile | Server | ||||||||||||
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Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
isExtensible |
49
|
12
|
42
|
No
|
36
|
10
|
49
|
49
|
42
|
36
|
10
|
5.0
|
1.0
|
6.0.0
|
See also
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Reflect/isExtensible