Mastering Immutable.js

Rendering the result count

Let's add a separate side-effect function that updates the result count:

const app = App(Map.of(  Map.of(...),  Map.of(    'results', Seq.of(      (results) => {        const count = results          .get('episodes')          .toSeq()          .filter(filter(results.toJS()))          .count();        document          .getElementById('results')          .querySelector('h3')          .textContent = document          .getElementById('results')          .querySelector('h3')          .textContent          .replace(/\d*/, count);      },    )  )));

In this case, we're executing the same query that's executed when the episodes are rendered, except in this function, we're counting values instead of iterating over the results. On the one hand, we have a separate side-effect function to handle rendering the result count. On the other hand, we're being ...