JS: Reflect.isExtensible
New in JS2015.
Reflect.isExtensible(obj)
-
Return
true
if obj is extensible. Else,false
.If obj is not object, throw a TypeError exception.
const jj = {}; console.log(Reflect.isExtensible(jj)); Reflect.preventExtensions(jj); console.log(Reflect.isExtensible(jj) === false);