Mastering Immutable.js

Setting map values

The set() method for maps is used to add and to change collection values. If the key that's being set doesn't exist, then the key-value pair is set for the first time. If the key does exist, then the previous value of that key is replaced with the new value, as follows:

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

Calling set() produces a new map, because all Immutable.js mutations are persistent changes.