Introduction
State management has long been a hotly debated subject in the React world. Best practices have continued to evolve, and there’s still a lot of confusion around the subject. In this article, we are going to dive into what tools we might want to use for solving common problems we face in modern web application development. There are different types of state and different types of ways to store and manage your application state. For example, you might have some local client state in a component that controls a dropdown, and you might also have a global store that contains authenticated user state. Aside from those typical examples, on some pages of your website, you might store some state in the URL.
For quite a while, we’ve been leaning into global client state in single-page app land. This is what state management tools like Redux and other similar libraries help us out with. In this post, we will cover these different strategies in more detail so that we can try to make the best decisions going forward regarding state management in our applications.
Local and global client state
In this section, we'll discuss the differences between local and global client state, when to use each, and some popular libraries that can help you manage them effectively.
When to use local client state
Local client state is best suited for managing state that is specific to a single component or a small group of related components. Examples of local state include form inputs, component visibility, and UI element states like button toggles. Using local state keeps the component self-contained, making it easier to understand and maintain. In general, it's a good idea to start with local state and only use global state when you have a clear need for it. This can help keep your code simple and easy to understand.
When to use global client state
Global client state is useful when you have state that needs to be accessed by multiple unrelated components, or when the state is complex and would benefit from a more carefully designed API. Common examples of global state include user authentication, theme preferences, and application-wide settings. By centralizing this state, you can easily share it across the entire application, making it more efficient and consistent.
If you’re building out a feature that has some very complex state requirements, this could also be a good case for using a “global” state management library. Truth is, you can still use one of these libraries to manage state that is actually localized to your feature. Most of these libraries support creating multiple stores. For example, if I was building a video chat client like Google Meets with a lot of different state values that are constantly changing, it might be a good idea to create a store to manage the state for a video call. Most state management libraries support more features than what you get out of the box with React, which can help design a clean and easy to reason about modules and APIs for scenarios where the state is complex.
Popular libraries for global state management
There are a lot of great libraries for managing state in React out there these days. I think deciding which might be best for you or your project is mostly a matter of preference.
Redux and MobX are a couple of options that have been around for quite a long time. Redux has gained a reputation for being overly complex and requiring a lot of boilerplate code. The experience is actually much improved these days thanks to the Redux Toolkit library. MobX provides an easy-to-use API that revolves around reactive data/variables. These are both mature and battle-tested options that are always worth considering.
Meta also has a state management named Recoil that provides a pretty easy-to-use API that revolves around the concept of atoms and selectors. I don’t see this library being used a ton in the wild, but I think it’s worth mentioning.
A couple of the more popular new players on the block are named jotai and zustand. I think after the Redux hangover, these libraries showed up as a refreshing oasis of simplicity. Both of these libraries have grown a ton in popularity due to their small byte footprints and simple, straightforward APIs.
Context is not evil
The React Context API, like Redux, has also been stigmatized over the years to the point where many developers have their pitchforks out, declaring that you should never use it. We leaned on it for state management a bit too much for a while, and now it is a forbidden fruit. I really dislike these hard all-or-nothing stances though. We just need to be a little bit more considerate about when and where we choose to use it.
Typically, React Context is best for storing, and making available global state that doesn’t change much. Some of the most common use cases are things like themes, authentication, localization, and user preferences. Contrary to popular belief, only components (and their children) that use that context (const context = useContext(someContext);) are re-rendered in the event of a state change, not all of the children below the context provider.
Storing state in the URL
The most underused and underrated tool in the web app state management tool belt is using the URL to store state. Storing state in the URL can be beneficial for several reasons, such as enabling users to bookmark and share application state, improving SEO, and simplifying navigation. The classic example for this is filters on an e-commerce website. A good user experience would be that the user can select some filters to show only the products that they are looking for and then be able to share that URL with a friend and them see the same exact results. Before you add some state to a page, I think it’s always worth considering the question: “Should I be able to set this state from the URL?”.
Tools for managing URL state
We typically have a couple of different tools available to use for managing URL state. Built-in browser APIs like the URL class and URLSearchParams. Both of these APIs allow you to easily parse out parts of a URL. Most often, you will store URL state in the parameters.
In most React applications, you will typically have a routing library available to help with URL and route state management as well. React Router has multiple hooks and other APIs for managing URL state like useLocation that returns a parsed object of the current URL state.
Keeping URL and application state in sync
The tricky part of storing state in the URL is when you need to keep local application state in sync with the URL values. Let’s look at an example component with a simple name component that stores a piece of state called name.
import React, { useState, useEffect } from 'react';
import { useLocation, useHistory } from 'react-router-dom';
function MyComponent() {
const location = useLocation();
const history = useHistory();
const [name, setName] = useState('');
useEffect(() => {
// Update the name state when the URL changes
const searchParams = new URLSearchParams(location.search);
setName(searchParams.get('name') || '');
}, [location]);
function handleNameChange(event) {
setName(event.target.value);
// Update the URL when the name changes
history.push(`/my-component?name=${event.target.value}`);
}
return (
<div>
<input type="text" value={name} onChange={handleNameChange} />
</div>
);
}
The general idea is to pull the initial value off of the URL when the component mounts and set the state value. After that, in our event handler, we make sure to update the URL state as well as our local React state.
Moving state to the server
Moving web application state to the server can be beneficial in several scenarios. For example, when you have a complex state that is difficult to manage on the client-side. By moving the state to the server, you can simplify the client-side code and reduce the amount of data that needs to be transferred between the client and server. This can be useful for applications that have a lot of business logic or complex data structures. In most cases if there’s some logic or other work that you can move off of your client web application and onto the server that is a win.
Conclusion
State management is a crucial aspect of building modern web applications with React. By understanding the different types of state and the tools available for managing them, you can make informed decisions about the best approach for your specific use case. Remember to consider local and global client state, URL-based state, and server-side state when designing your application's state management strategy.
