How to check if object is Immutable?

Question

Immutable object can be an instance of:

• Immutable.List
• Immutable.Map
• Immutable.OrderedMap
• Immutable.Set
• Immutable.OrderedSet
• Immutable.Stack

Answer 1

There is an open ticket to improve the API which is on the roadmap for 4.0. Until this is implemented, I suggest you use Immutable.Iterable.isIterable() (docs).

Using instanceof is not reliable (e. g. returns false when different modules use different copies of Immutable.js)

Answer 2

I have learned that using instanceof to determine wether object is Immutable is unsafe:

Module A:

var Immutable = require('immutable');
module.exports = Immutable.Map({foo: "bar});

Module B:

var Immutable = require('immutable');
var moduleA = require('moduleA');
moduleA instanceof Immutable.Map // will return false

Immutable.js API defines the following methods to check if object is an instance of Immutable:

• Map.isMap()
• List.isList()
• Stack.isStack()
• OrderedMap.isOrderedMap()
• Set.isSet()
• OrderedSet.isOrderedSet()

and

• Iterable.isIterable()

The latter checks if:

True if an Iterable, or any of its subclasses.

List, Stack, Map, OrderedMap, Set and OrderedSet are all subclasses of Iterable.