10 React Context Best Practices
The React Context API can be a great way to manage state in your React applications. However, there are a few best practices to keep in mind when using it.
React Context is a powerful feature that allows you to share data throughout your React app without having to pass props down manually at every level. When used correctly, it can make your code more concise and easier to reason about.
However, because Context is such a flexible tool, it’s important to be aware of some best practices to avoid potential problems down the road. In this article, we’ll discuss 10 React Context best practices that will help you get the most out of this feature.
1. Don’t use context unless you have to
React Context is a powerful feature, but it comes with some trade-offs. The biggest one is that using Context creates tight coupling between the provider and the consumers. This means that if you ever need to change the shape of the data in the context, all the consumers will have to be updated as well.
So, unless you have a very good reason to use React Context, it’s best to avoid it. If you do need to use it, make sure you document the shape of the data in the context, so it’s easy to update the consumers if necessary.
2. Use a single provider at the top level of your app
If you have multiple providers, each provider will create its own separate context. That means if you have a consumer that needs data from both providers, it will need to subscribe to both contexts, which can be confusing and lead to bugs.
It’s also difficult to keep track of which provider is used where if you have multiple providers. By using a single provider, you can more easily keep track of which context your consumers are using and where.
3. Use multiple consumers when nesting becomes too complex
If you have a deeply nested component, and you only need the data from the context in a few places, using multiple consumers can make your code more readable. It can also help performance because React will only re-render the components that are using the specific data that changed.
For example, let’s say you have a context with a “theme” object. The theme object has a “color” property, and you want to use that color in two different places in your app.
Instead of using one consumer and passing the “theme” object down through all of the intermediate components, you can use two consumers. One consumer can be used for the first place you need the color, and the other consumer can be used for the second place.
This way, if the “theme” object changes, React will only re-render the components that are using the specific data that changed.
4. Don’t put stateful logic in context, use custom hooks instead
If you put stateful logic in context, it will be harder to test and debug because you won’t be able to access the state directly. Additionally, if you need to change the stateful logic, you’ll have to do it in multiple places.
Custom hooks, on the other hand, are much easier to test and debug because they’re self-contained and don’t rely on context. Plus, if you need to change the stateful logic, you can just update the hook.
5. Avoid using context for passing props deeply through the component tree
When you pass props using context, those props are available to all components that are descendants of the provider component in the component tree. This means that if a prop changes, all components that receive that prop will re-render.
For example, let’s say you have a component that renders a list of items. Each item in the list has a delete button. When the delete button is clicked, the item is removed from the list.
If you use context to pass the list of items down to the child components, then when an item is deleted, all of the child components will re-render because the list of items has changed.
Instead of using context, it’s better to pass the props directly to the child components that need them. That way, only the components that need to re-render will actually do so.
6. Always define default values for your context
If a consumer tries to access a context value that hasn’t been set yet, React will throw an error. This is by design, and it’s meant to help catch bugs early on. However, it can be annoying in development because you might not always have all the context values set up right away.
To avoid this, you can use the defaultValue prop when creating your context. This will give your context a default value that consumers can fall back on if they try to access a context value that isn’t set yet.
This is especially important when you’re using multiple contexts in your application. If you don’t set default values for each context, then accessing any context value could potentially cause an error.
7. Prefer function components over class components
Function components are simpler to write and understand than class components. They’re also more efficient because they don’t have the overhead of a class component (such as lifecycle methods).
Class components can be used when you need state or lifecycle methods, but in most cases, function components will suffice.
8. Make sure that all consumers are wrapped in providers
If a consumer is not wrapped in a provider, then it will never re-render when the context value changes. This means that if you ever need to update the context value (for example, when a user logs in or out), any consumers that are not wrapped in providers will not update accordingly.
This can lead to bugs and inconsistencies in your application, so it’s always best to make sure that all consumers are wrapped in providers.
9. Be careful with re-renders and avoid unnecessary renders
Re-rendering is expensive, and when you’re re-rendering unnecessarily, you’re wasting resources. So, be sure to only re-render when necessary. React provides a few ways to help with this, such as shouldComponentUpdate, PureComponent, and memo.
Additionally, avoid unnecessary renders by only subscribing to the context changes that your component needs. If you’re subscribed to too many context changes, you’ll end up with more re-renders than necessary.
Finally, make sure to batch context updates together. When multiple context values update at different times, React will re-render for each one individually. However, if you batch them together into a single setContext call, React will only re-render once.
10. Test your context API code
When using Context, you’re essentially creating a global state. This means that any changes to your context will impact every component that uses it. As such, it’s important to make sure that your context is working as intended, and that any changes you make don’t break your app.
The best way to do this is to write unit tests for your context code. That way, you can be confident that your context is working as expected, and that any changes you make won’t break your app.