Mastering Immutable.js

Strict equality versus deep equality

Strict equality has limited utility compared to deep equality. Strict equality is great for efficiently checking if a collection has changed after calling a mutative method. In fact, you can use either strict equality or deep equality to check if a collection has changed:

const myMap = Map.of('first', 1);const myModifiedMap = myMap.set('first', 'first');const myUnmodifiedMap = myMap.set('first', 1);console.log('myMap', myMap.toJS());// -> myMap { first: 1 }console.log('myModifiedMap', myModifiedMap.toJS());// -> myModifiedMap { first: 'first' }console.log('myUnmodifiedMap', myUnmodifiedMap.toJS());// -> myUnmodifiedMap { first: 1 }console.log(  'myMap === myModifiedMap',  myMap === myModifiedMap);// -> myMap ...