Mastering Immutable.js

Creating new episodes

When we create a new episode and add it to the list of episode maps, we're actually updating two pieces of state. We're updating the results state because this is where the episodes list is located. We're also updating the create state to reset the form field values back to empty strings:

document  .querySelector('form[name="create-episode"]')  .addEventListener('submit', (e) => {    e.preventDefault();    app(state => state      .updateIn(        ['results', 'episodes'],        episodes => episodes.push(          Map(state.get('create').toJS())        )      )      .setIn(['create', 'title'], '')      .setIn(['create', 'director'], '')      .setIn(['create', 'date'], '')    );  });

Here we're chaining together several mutative methods that change the state of the application. First, ...