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.
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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
A TypeError
, if target
is not an Object
.
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
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Reflect.isExtensible' in that specification. |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
isExtensible | Chrome Full support 49 | Edge Full support 12 | Firefox Full support 42 | IE No support No | Opera Full support 36 | Safari Full support 10 | WebView Android Full support 49 | Chrome Android Full support 49 | Firefox Android Full support 42 | Opera Android Full support 36 | Safari iOS Full support 10 | Samsung Internet Android Full support 5.0 | nodejs Full support 6.0.0 |
Legend
- Full support
- Full support
- No support
- No support