Copyright 2018 Basefactor. Most of us are very used to the global state concept and we have been applying this pattern in our apps extensively. That's not how Redux worked, right? This is great! Sometimes you want global state in React, but you don't want the added complexity of using Redux. As we discovered the cleanliness and simplicity of hooks, Redux started to feel like overly complex and verbose with all those containers, reducers, action creators and so on.
But, for whatever reason, what if we want to have a complex object in context serving as a global state? In this post we will go through several techniques to mitigate this problem: If you want to read more details about how this works, keep on reading :). Now, with the introduction of the Context API in version 16.3 and Hooks in version 16.8, it can be done from within React and without installing any third-party dependency.
Finally, we have presented a few implementations to overcome this problem by either splitting context, blocking undesired re-renders with containers or relaying in a third party solution. … This … Ken C Dodds goes a step further and suggests not only splitting context but also keeping state as close to where it's needed as possible. Wrap your components with gs. yarn add react-global-state. However, we could go a bit further and build a more flexible solution as most of your scenarios will require to not only consume global data but also modify it. As they stated: Context provides a way to pass data through the component tree without having to pass props down manually at every level, Maybe it goes beyond this and you get a good idea about … We have compiled the demos source code from this post in the following Github repo: global-state-react, Application State Management with React: https://kentcdodds.com/blog/application-state-management-with-react, Github facebook/react discussion, Provide more ways to bail out inside Hooks, React tracked library: https://github.com/dai-shi/react-tracked. In other words, every component subscribed to our global state will re-render upon a context change, which in some scenarios might lead to performance issues. What if calling setState could update your entire state tree?
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To better understand the consequences of this issue, now think about the previous Counter component: it only uses num property from global state, so it only needs to be informed whenever num is changed. We can't modify text in any way. Usage.
To better illustrate this issue, we have built a demo for you: I know what you are thinking: it would be desirable to let useContext subscribe only to a part of the context value (like a selector) to avoid over re-rendering.
However, Counter will re-render upon bool or text changes, even if num remains the same, but Counter doesn't care about bool or text properties! Again, inspired by options 2 and 3 by Abramov, we can wrap our components by containers that filter out undesired global state updates. This solution mimicks what was done by Redux containers: listening to global state changes but only passing down the desired part of the state through props. Once you went through this state management in React walkthrough, you should have a good grasp of what's state in React. In this post, we are going to show you the main issues of this pattern and a few different approaches to achieve global state using React native features. Even if you just consider the first basic sample with static global state, or our proposal in the previous section, or any other solution of your own based on React context, all of them will suffer from a common problem: useContext hook will re-render whenever your context is modified. So, in summary, all our components "connected" to the global state will re-render under any minimal change in that state, even if it does not affect them directly. Yes I know, this wouldn't be a 100% native solution, but it provides performance and ease of use at a minimum cost, so it's worth checking it out. Just wrap your app within a context provider and feed that provider with the data you want to make global: Consumption of this data is a piece of cake thanks to the hooks: just retrieve your state by using useContext hook wherever you need it: In the previous example we just did a basic approach: consuming a static global state.
react-global-state. Bye Redux! npm install --save react-global-state.
React context suffers from a common problem: useContext hook will re-render whenever your context is modified. useMemo... amongst others.
There are plenty of third party libraries aiming to provide a single place to store our state, but when we are talking about React, Redux is the king in that regard.
In this article we assume that you are already familiar with React Hooks, we will make use of useReducer, useCallback, Certainly, context was a high-value addition to React. You can learn more about it in the official hooks api reference. In order to consume this global state, we opted for creating a custom hook that exposes both state and dispatch in a single call: So, accessing global state from a component can be as easy as this: Of course, it is important to note that this is not the only valid implementation to accomplish global state within React and you may have your own. For the sake of usefulness and completeness, we have added a few more properties in our global state: num, text and bool.
It will provide us with a single and constant dispatch method to trigger global state updates. more info about it in this link. Based on the previous solutions, the correct usage of React context seems to imply breaking it into smaller pieces to avoid performance issues. C/ Pintor Martínez Cubells 5 Málaga (Spain). Well, Dan Abramov himself got involved in this discussion and offered some tips. The question didn't take too long; if new React context was designed to feed a whole component tree with data, wouldn't it be possible to redefine the global state pattern by using native context plus hooks?
This idea of multiple contexts is gaining traction in the community.
Even though this solution moves away from having a single global context, it is a very interesting approach to manage state natively in React. So far, useContext has been working as designed and the problem is closer to the pattern itself: we are trying to keep unrelated properties under a single context. For that purpose, let's bring useReducer into the equation. Before you blame the React team, I will tell you that this topic has an open discussion in the React community.
If storing everything in a monolith context is problematic, let's split context separating unrelated data. The following approach is built on top of Daishi Kato's react-tracked, a library which is only 1.5kB and has superb performance, aimed to deal with complex objects in context without the hassle of unnecessary re-renders. Hence you cannot have a real global state in React.
Actually, this is the exact reason why Redux dropped their experimental approach of using direct React context. With the release of context API in React 16.3 and especially hooks in React 16.8, a new world of possibilites suddenly arose. However, by deploying the right React techniques, you can actually have a global state in React without having to use Redux. We have demonstrated the issue with useContext, whose subscription-like mechanism triggers a re-render on every state update, regardless of whether that update is significant for our component or not. We can make data accessible to many different components regardless its level in the tree, that is to say, we can subscribe components to a "global" data store. And since React is a library, creating and managing a global state requires a third-party dependencies like Redux. Although containers will re-render on every context update, they are very light and cheap components to minimize performance issues.
If you need coaching or consultancy services, don't hesitate to contact us. or. Then, let's make dispatch available to our components through a separate context; sort of having 2 "channels", one to consume global data and another one to modify it. All Rights Reserved. Now, we could re-write our Counter example like this: And Counter would only re-render whenever state.num is updated, ignoring the rest of the properties in our global state. Creating a global state in React is one of the first signs that you may need Redux (or another state management library such as MobX) in your application, because in React the local state is located on a component level. https://kentcdodds.com/blog/application-state-management-with-react, Provide more ways to bail out inside Hooks. In order to consume this global state, we opted for creating a custom hook that exposes both state and dispatch in a single call: const useGlobalState = () => [ React.useContext(GlobalStateContext), React.useContext(DispatchStateContext) ]; So, accessing global state from a …
In other words, every component subscribed to our global state will re-render upon a context change. I bet most of you have been in touch with Redux for quite a long time. We will start with simple state management that is co-located to React components, exploring all its features with React Hooks, and end with more complex global state in React managed by React itself or third-party libraries. This may lead to performance issues. In this article, we have explored several approaches to manage global state using native React context, dropping complex Redux implementations and embracing the cleanliness of hooks.