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Other References

CSSStyleDeclaration JS Conversion


JavaScript Object.isExtensible()

Example

// Create Object
const person = {firstName:"John", lastName:"Doe"};

// Prevent Extensions
Object.preventExtensions(person);

// This will return false
let answer = Object.isExtensible(person);
Try it Yourself »

More Examples Below !


Description

The Object.isExtensible() returns true if an object is extensible.


Related Methods:

Object.preventExtensions() allows modifications, but prevents addition of properties.

Object.seal() allows modifications, but prevents additions and deletions of properties.

Object.freeze() prevents modifications, additions and deletions of properties.


Object.isExtensible() returns true if an object is extensible.

Object.isSealed() returns true if an object is sealed.

Object.isFrozen() returns true if an object is frozen.


Syntax

Object.isExtensible(object)

Parameters

Parameter Description
object Required.
The object to check.

Return Value

Type Description
Booleantrue if the object is extensible.
false if not.

More Examples

Example

// Create Array
const fruits = ["Banana", "Orange", "Apple", "Mango"];

// Prevent Extensions
Object.preventExtensions(fruits);

// This will return false
let answer = Object.isExtensible(fruits);
Try it Yourself »

Browser Support

Object.isExtensible() is an ECMAScript5 (ES5) feature.

ES5 (JavaScript 2009) is fully supported in all modern browsers since July 2013:

Chrome
23
IE/Edge
11
Firefox
21
Safari
6
Opera
15
Sep 2012 Sep 2012 Apr 2013 Jul 2012 Jul 2013

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