Immutable JS compare nested structures

Question

I have 2 nested structures newState and newState1.

But when I compare their, equals() or Immutable.is() returned false

Answer 1

It seems that immutablejs don't do deep conversion, so if your value is object, it stays to be object.

As you're creating different object in each update step, and those objects will be treat different when you compare to each other, so you should also convert it to Immutable.Map object, to make the compare be true.

// Primitives.
var test1 = Immutable.Map({
    a: 'a', 
    b: 'b', 
    c: 'c'
});
var test2 = Immutable.Map({
    a: 'a',
    b: 'b',
    c: 'c'
});
console.log('Test primitive', test1.equals(test2)); // true

// Object
test1 = Immutable.Map({
    a: 'a',
    b: 'b',
    c: {}
});
test2 = Immutable.Map({
    a: 'a',
    b: 'b',
    c: {}
});
console.log('Test object', test1.equals(test2));  // false
// Its because
var a = {};
var b = {};
console.log('a === b?', a === b); // false

// Convert
test1 = Immutable.Map({
    a: 'a',
    b: 'b',
    c: Immutable.Map({})
});
test2 = Immutable.Map({
    a: 'a',
    b: 'b',
    c: Immutable.Map({})
});
console.log('Test converted', test1.equals(test2)); // true

<script src="https://cdnjs.cloudflare.com/ajax/libs/immutable/3.7.5/immutable.min.js"></script>

Answer 2

What about using JSON.stringify?

JSON.stringify(values) !== JSON.stringify(anothervalue);

If you know they are not circular objects, and do not contain functions, I think it's the fastest way to compare them.

Answer 3

Change Immutable.Map to Immutable.fromJS in your push functions (as has been mentioned - only fromJS will do a deep conversion, Map,List etc won't):

var newState = state.updateIn(['widgets'], function (list) {
    return list.push(Immutable.fromJS({
        name: 'Some widget2',
        type: 'List',
        defaultDataSource: 'daily',
        dataSources: {}
    }));
});

var newState1 = state.updateIn(['widgets'], function (list) {
    return list.push(Immutable.fromJS({
        name: 'Some widget2',
        type: 'List',
        defaultDataSource: 'daily',
        dataSources: {}
    }));
});