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redux
Duke Dougal
Duke Dougal

Reputation: 26366

With React / Redux, is there any reason not to program the store globally?

I love Redux, but to use it, I have LOTS of additional code scattered all over my application: connect, mapDispatchToProps, mapStateToProps etc etc

It appears to me however that I should be able to both dispatch to the store and get any value from the store via a global window level reference to the store object. If I did this, it would cut alot of code out of my application.

So the question is, what is wrong with this approach? Why NOT do all my Redux disptach and state access via window.store?

Upvotes: 1

Views: 221

Answers (1)

markerikson
markerikson

Reputation: 67539

I wrote a long Reddit comment a while back about why you should use the React-Redux library instead of writing store code by hand.

Quoting the main part of that answer:

First, while you can manually write the code to subscribe to the Redux store in your React components, there's absolutely no reason to write that code yourself. The wrapper components generated by React-Redux's connect function already have that store subscription logic taken care of for you.

Second, connect does a lot of work to ensure that your actual components only re-render when they actually need to. That includes lots of memoization work, and comparisons against the props from the parent component and the values returned by your mapStateToProps function for that component. By not using connect, you're giving up all those performance improvements, and your components will be unnecessarily re-rendering all the time.

Third, by only connecting your top-level component, you are also causing the rest of your app to re-render unnecessarily. The best performance pattern is to connect lots of components in your app, with each connected component only extracting the pieces of data it actually needs via mapStateToProps. That way, if any other data changes, that component won't re-render.

Fourth, you're manually importing the store into your components, and directly coupling them together, thus making it harder to test the components. I personally try to keep my components "unaware" of Redux. They never reference props.dispatch, but rather call pre-bound action creators like this.props.someFunction(). The component doesn't "know" that it's a Redux action creator - that function could be a callback from a parent component, a bound-up Redux action creator, or a mock function in a test, thus making the component more reusable and testable.

And finally, the vast majority of apps built using React and Redux use the React-Redux library. It's the official way to bind the two together, and doing anything else will just confuse other developers looking at your project.

Also, per the Redux FAQ entry on importing the store directly:

While you can reference your store instance by importing it directly, this is not a recommended pattern in Redux. If you create a store instance and export it from a module, it will become a singleton. This means it will be harder to isolate a Redux app as a component of a larger app, if this is ever necessary, or to enable server rendering, because on the server you want to create separate store instances for every request.

Summarizing all that:

  • Better performance
  • Lower coupling via dependency injection of the store
  • Better testability
  • Better architecture

I'd also suggest you read through my two-part post The Tao of Redux, Part 1 - Implementation and Intent, and The Tao of Redux, Part 2 - Practice and Philosophy. These two posts discuss the history and intent behind Redux's design, how it's meant to be used, why common usage patterns exist, and other ways that people may use Redux.

Upvotes: 2

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