Reflect.isExtensible()
Reflect.isExtensible() is a JavaScript method in the Reflect category. Checks if target is extensible. The syntax is Reflect.isExtensible(target). A typical example: Reflect.isExtensible({}) // true. A close sibling is Reflect.get(), which gets a property. A close sibling is Reflect.set(), which sets a property. A close sibling is Reflect.has(), which like the in operator. A close sibling is Reflect.preventExtensions(), which prevents extensions on target. More about this category: Reflect API for meta-programming. Related Reflect methods: Reflect.get(), Reflect.set(), Reflect.has(), Reflect.preventExtensions(), Reflect.getOwnPropertyDescriptor(), Reflect.defineProperty(), Reflect.getPrototypeOf(), Reflect.setPrototypeOf(). This page is part of the free JS Reference documentation covering 1027+ methods, each with syntax, parameters, return values, examples, and common pitfalls. You can try Reflect.isExtensible() immediately in the JavaScript playground, look up unfamiliar terms in the glossary, or return to the JS Reference homepage.