Reflect.preventExtensions()

The Reflect.preventExtensions() static method is like Object.preventExtensions(). It prevents new properties from ever being added to an object (i.e., prevents future extensions to the object).

Reflect.preventExtensions() provides the reflective semantic of preventing extensions of an object. The differences with Object.preventExtensions() are:

Reflect.preventExtensions() throws a TypeError if the target is not an object, while Object.preventExtensions() always returns non-object targets as-is. Reflect.preventExtensions() returns a Boolean indicating whether or not the target was successfully set to prevent extensions, while Object.preventExtensions() returns the target object.

Reflect.preventExtensions() invokes the [[PreventExtensions]] object internal method of target.

Syntax example: Reflect.preventExtensions(target)