React will not recompute/re-render your component.. useReducer() is used when you’d rather modify state via reducers and actions. All your 27 developers can mutate them by design or by mistake. Now if ThemedButton was a class component we would be able to extract the context with contextType. The LogRocket Redux middleware package adds an extra layer of visibility into your user sessions. Redux’s implementation of a global store means that the store itself isn’t tied to any component; it’s separate from your app. useCallBack() makes sure that the function passed down to component only changes if its dependency (counter) change. The Consumer component however requires a function as a child like render props. So let's make a simple React app. Easy to Use. Accidental state change should be avoided as much as possible. Every React developer faced this challenge before: The need to share state between non-connected components. React functional components are plain JavaScript functions. It must be approached with respect since it is where you can create the worst regressions. What are hooks? For instance, take these two separate stores and their dispatch functions: Because of the dependence of the dispatch function on the useReducer call that returned it, you can’t use dispatch1 to trigger state updates in authStore, nor can you use dispatch2 to trigger state updates in notificationStore. Sharing state between components. We’ll see how they look below and then explain in detail what each of them is used for. Now, every Context object comes with a Provider and a consumer. Here the onClickHandler() function fails referential equality because a different function is created during every Parent render. It is not possible to persist state in local variables as these are initialized every time the function is evaluated. This prompts the child to re-render more than it needs to. For simple types, using const keyword protects the state from direct mutation. It is important to remember that props, passed in as function arguments from the component owner are also part of the component state. A React application usually can be divided into multiple features. If we were using Redux, we’d have had to use Provider to wrap all the components, create a separate store, and then for each component that needs to connect to the store, wrap them in a HOC with connect. When it changes, it triggers recalculations or re-rendering of all the visible React components. We could have as many stores, reducers, initialStates, etc. This will allow the children components to read from and update the store as required. Now for the reason you’re actually reading this article. Context is often touted as a lightweight alternative to Redux and provides much cleaner and simpler code. const increment = () => ({ type: "increment" }); compute(1, 2); // call computeExpensiveValue(1, 2). One of my favorite Hooks so far is useReducer, which allows you to handle complex state updates, and that’s what we’ll be looking at in this article. Now, why should I abandon one of the most beloved libraries for React state management? This way, instead of sprinkling your state mutation logic throughout your component/container, it is tucked away inside a reducer. Well, as you can see above, we have to thread the theme property through all the components, so that we can apply it to child elements. Bind dispatch function to your action functions. OK, let’s write a login function, call it from the component, and watch how the store gets updated. Open source and radically transparent. The toggle function from the global Context is then called by the button in a child component, which thus updates the global Context. In the code snippet above, we have defined an initial state for our component — a reducer function that updates that state depending on the action dispatched — and we initialized the state for our component on line 21. create your reducer and actions to manage your feature state. Now ordinarily, to pass states down to child components what we do is pass down props. There are some rather important limitations to useReducer that we need to talk about if we’re being objective. Here is the usage: The difference between useState() and useRef() is that a component will not refresh when you mutate the ref’s current value. Yeah you are both right, my mistake...But still, the component will re-render even if the values that it's using from that Context instance don't change. Use create-react-app to generate one. I believe that architecturally, your application features and its state should be managed in isolation and co-located. Function internal variables will get initialized during each execution. We know what a reducer is now and how it determines the next state for your component through actions being dispatched. In this article, we’ll cover the basics of RxJS and how to integrate it with React applications using React Hooks for state management.