Often you need to deeply update an complex Map or List. Using Immutable.js .update() is a powerful way to this kind of update.
Given this state
const = myState = Immutable.Map({'123': Immutable.Map({id: 123,b: false,}),'456': Immutable.Map({id: 456,b: true,}),}); |
Don’t use .get() then .set()
const myUpdatedItem = myState.get('123').set('b', true);const myNewState = myState.set('123', myUpdatedItem); |
Using .get() then .set() seems simple and clean, but it’s slow, it fully replaced the the current Map. While the results are the same, ImmutableJS cannot optimize against it and cannot make some faster assumptions.
Using Immutable.js .update()
const myNewState = myState.update('123', (myMap) => {return myMap.set('b', true);} ); |
It is much better to using Immutable.js .update(). Immutable can keep more references and make assumptions that allow it to optimize the update. For more, check the .update() docs.
You can also use .updateIn() for deeply nested data. Read my post on Immutable get() vs .getIn() to see how it works.