So far, we have an application that provides the initial state and then updates this state in response to user interactions. The final thing we need to build are the actual side-effect functions that execute in response to changing the state.
Any piece of state within the results state has the potential to change what's rendered on the screen. If an episode is added, removed, or changed, the list needs to be rendered. If a filter control changes, the list needs to be rendered because the current list might not reflect the current filter settings.
We'll still use the same filtering approach used in Chapter 14, Side-Effects in User Interfaces, though with a few minor adjustments:
const filter = ({
query,
title,
date,
director,
rating
}) => every(
some(
() => query === undefined,
() => query === '',
every(
() => title,
v => v.get('title').includes(query)
),
every(
() => date,
...