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.
Reflect.preventExtensions(target)
target
A Boolean
indicating whether or not the target was successfully set to prevent extensions.
A TypeError
, if target
is not an Object
.
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()
.
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
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
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.preventExtensions' in that specification. | Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'Reflect.preventExtensions' in that specification. | Draft |
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 49 | 12 | 42 | No | 36 | 10 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
---|---|---|---|---|---|---|---|
Basic support | 49 | 49 | Yes | 42 | 36 | 10 | ? |
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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/preventExtensions