JS: Reflect.preventExtensions

By Xah Lee. Date: . Last updated: .

New in ES2015.

Reflect.preventExtensions ( obj )

Sets obj's extensible attribute to false.

Return true if success, else false.

If obj is not object, throw a TypeError exception.

const u = {};
console.log ( Reflect.isExtensible ( u ) ); // true
Reflect.preventExtensions ( u );
console.log ( Reflect.isExtensible ( u ) ); // false

Reflect.preventExtensions vs Object.preventExtensions?

What's the difference?

Object.preventExtensions(obj) return obj if obj is not a object.

[see JS: Object.preventExtensions]

Reference

ECMAScript® 2016 Language Specification#sec-reflect.preventextensions

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