![]() We changed our context value but now our default value doesn't make sense, it's still 0. It's important to know when to use useState and when to use useContext. Most of the time, useState is enough for your needs. As it's usually shared between a bunch of components, it can cause performance issues when abused and used for the wrong kind of state. If you notice that your context is holding two values that are completely unrelated to each other, consider splitting them into different contexts.Īre you noticing that your app is growing, there are too many contexts being created, and managing the state is becoming complex? Maybe it is time to use a state management library, such as Redux Toolkit or Recoil. React Context is a great tool, but it can also be dangerous. Re-rendering a couple of components is not a big deal, but as your context grows the performance of the app may get worse since changing a single value will update a lot of unrelated components. But as mentioned in the previous section, any changes will recreate the object, triggering a re-render in all the components that are consuming the context. Reacts Context API has become the state management tool of choice for many, oftentimes replacing Redux altogether. When you have your context created it might be tempting to add everything that you want to be global in there. By using this hook we are always receiving the same function reference, if we didn't do that the function would be different on every re-render making our useMemo pointless. Notice that we are now using the useCallback hook in the increment function. If any of the values in the dependency array is changed then a new object is created and our provider will correctly trigger a re-render in the consumers to reflect the new value. The hook will create the object only once and return the same reference on every re-render as long as the dependency array doesn't change. ![]() Since we already know how the React Context API looks like, we can base it on that.Export function CounterProvider ( Now that we have the general concept of how we’re going to use our context, let’s start by defining the functions we’re going to expose. Well, mostly - instead of our ContextProvider component, we’re using TextContext.Provider, which takes an object with the references to our values, and useContext() that serves as our portal - so we can tap into our wormhole. OK, so this is starting to look more like JavaScript. import = useContext(TestContext) Ĭonsole.log(description + " > ✅ " + text)Ĭonsole.log(description+ " > □ " + text) That Color component displays a message containing the message defined in its parent component - the app, only without having it being passed directly as a prop to the component, but rather - having it “magically” appear through the use of useContext. ![]() In the snippet below, we have our app that has a Color component in it. As mentioned, to use React context, you need to create a provider and a consumer. The following snippet is a rather simplistic (and pretty useless) example of React’s context API, but it demonstrates how we can use values defined higher up in the component tree without passing them explicitly to the child components. You can imagine React’s context as some kind of a “wormhole” that you can pass values through somewhere up your component tree and access them further down in your children’s components. “Context provides a way to pass data through the component tree without having to pass props down manually at every level.” In the world of React, context is used as an alternative to prop-drilling and synchronizing state across different parts of the apps. React popularized the idea of context-propagation within our applications with its context API. This article brings a brief intro to context propagation in JavaScript and shows that there’s no magic at all behind some of the most useful React APIs. React popularized the idea of context-propagation within our applications with its context API, an alternative to prop-drilling and synchronizing states across different parts of the apps. ![]()
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