Maps are Iterable

Maps in Immutable.js are iterable, meaning that you can map, filter, reduce, etc. each key-value pair in the map.

let features = Immutable.Map<string, boolean>({
    'send-links': true,
    'send-files': true,
    'local-storage': true,
    'mirror-notifications': false,
    'api-access': false
});
let myFeatures = features.reduce((providedFeatures, provided, feature) => {
    if(provided)
        providedFeatures.push(feature);
  return providedFeatures;
}, []);
console.log(myFeatures); // [ 'send-links', 'send-files', 'local-storage' ]

const mapMap = Immutable.Map({ a: 0, b: 1, c: 2 });
mapMap.map(i => i * 30);
const mapFilter = Immutable.Map({ a: 0, b: 1, c: 2 });
mapFilter.filter(i => i % 2);
const mapReduce = Immutable.Map({ a: 10, b: 20, c: 30 });
mapReduce.reduce((acc, i) => acc + i, 0);

原文: https://angular-2-training-book.rangle.io/handout/immutable/immutable-js/nested-objects/maps_are_iterable.html