JS: Reflect.isExtensible

By Xah Lee. Date: . Last updated: .

New in ES2015.

Reflect.isExtensible (obj)

Return true if obj is extensible. Else, false.

If obj is not object, throw a TypeError exception.

[see JS: Prevent Adding Property]

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

Reflect.isExtensible vs Object.isExtensible?

What's the difference?

Object.isExtensible(obj) return false if obj is not a object.

[see JS: Object.isExtensible]

Reference

ECMAScript® 2016 Language Specification#sec-reflect.isextensible

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