Reflect.preventExtensions()
The static Reflect
.preventExtensions()
method prevents new properties from ever being added to an object (i.e. prevents future extensions to the object). It is similar to Object.preventExtensions()
, but with some differences.
Syntax
Reflect.preventExtensions(target)
Parameters
target
- The target object on which to prevent extensions.
Return value
A Boolean
indicating whether or not the target was successfully set to prevent extensions.
Exceptions
A TypeError
, if target
is not an Object
.
Description
The Reflect.preventExtensions
method allows you to prevent new properties from ever being added to an object (i.e. prevents future extensions to the object). It is the same method as Object.preventExtensions()
.
Examples
Using Reflect.preventExtensions()
See also Object.preventExtensions()
.
// Objects are extensible by default. var empty = {}; Reflect.isExtensible(empty); // === true // ...but that can be changed. Reflect.preventExtensions(empty); Reflect.isExtensible(empty); // === false
Difference to Object.preventExtensions()
If the first argument to this method is not an object (a primitive), then it will cause a TypeError
. With Object.preventExtensions()
, a non-object first argument will be coerced to an object at first.
Reflect.preventExtensions(1); // TypeError: 1 is not an object Object.preventExtensions(1); // 1
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.preventExtensions' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Reflect.preventExtensions' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 49 | 42 (42) | 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 | 42.0 (42) | 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/reflect/preventextensions