On: Ask HN: I get React but not Redux

[eiriklv]

Redux can come off as a bit intimidating, but fortunately builds entirely on old ideas and concepts like publish/subscribe, reduce/fold and pure functions that takes a value + an event and returns a new value (reducer function).

Without the middleware support Redux pretty much boils down to this:

  function createStore(reducer) {
    let state = undefined;
    let subscribers = [];

    return {
      getState() {
        return state;
      },
      subscribe(subscriber) {
        subscribers.push(subscriber);
      },
      dispatch(action) {
        state = reducer(state, action);
        subscribers.forEach(subscriber => subscriber());
      }
    };
  }

The advantage of Redux will start to show itself first when your app grows larger and you start doing things like consuming many different views/derivatives of the same state (using selectors) spread across your application.

Redux (core) doesn't actually solve the other big complexity culprit of big web applications though - asynchronous flow and side effects. For that you'll have to look into middlewares like redux-thunk or redux-saga, depending on your needs.

I'd suggest that instead of focusing on specific implementations such as Redux it's a good idea to take a look at those concepts + patterns like CQRS to get an understanding of why you'd want these things in the first place.

It's usually a good idea to feel the pain it alleviates before diving in at the deep end.

[eiriklv → eiriklv]

An alternative thought model of Redux could be represented like this:

  function createStore(reducer) {
    let actions = [];
    let subscribers = [];

    return {
      getState() {
        return actions.reduce(reducer, undefined);
      },
      subscribe(subscriber) {
        subscribers.push(subscriber);
      },
      dispatch(action) {
        actions.push(action);
        subscribers.forEach(subscriber => subscriber());
      }
    };
  }

If you start out by digging into how Array.reduce works you're 90% there, which is where the name "Redux" comes from.