React useReducer Guides
useReducer allows for custom state logic.
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A reducer function receives two arguments, the first one is the state, that we are passing when using
useReducerhook, and the second one is an object that represents that events and some data that will change the state (action).
This is going to be one of the best post you have ever come across in search of useContext + useReducer hooks!
The useReducer hook is used for complex state manipulations and state transitions. … useReducer is a React hook function that accepts a reducer function, and an initial state. const [state, dispatch] = useReducer(reducer, initialState);This hook function returns an array with 2 values.
Is your components are complex with too many states and props?. its time to use useReducer and useContext hooks now to make them simple and clean.
This works perfectly fine. But... if you want to use terse version of
this.setStatemethod in function component (or just have some fun) you can use
useReducerhook to do it.
useReducercan be used to simplify the way in which multiple states impact a piece of data. In this case, adding, removing, and clearing an array can be achieved by using
useReducerinstead of three separate states.
const [state, dispatch] = useReducer(reducer, initialState)I'm using
useReducerfunction from the react which gives me back the current state and the dispatch method to trigger actions.
This is super helpful, we added a global state to our app! But what if we wanted to update that state? That's where the useReducer comes into the picture.
UseReducer is one of the additional hooks that shipped with React 16.8 . It is an alternative to
useStatehook and helps in managing complex state logic that involves multiple sub-values or when the next state depends on the previous one. When combined with
useContextand other hooks, it can be a good alternative to redux.
useReduceralso lets you optimize performance for components that trigger deep updates because you can pass dispatch down instead of callbacks.
useReducerreturns a tuple
[state, dispatch]and takes three arguments,
initis optional and used for lazy initialization - more on that in a minute.
React-context-devtool is devtool for react context and useReducer hook.
Managing state in React can be quite tricky. Libraries like Redux make this more manageable as they only keep one source of truth (the store) that you interact with. In many cases though, this can be too complex to set up. In this tutorial I will show you how to use the React Context API together with the useReducer hook to avoid manually passing down props.
I quickly learned that
useReduceris a highly competent alternative to Redux and typing it (adding typescript types) is much more straightforward than it is with Redux. There was however one thing missing: Persistence.
We dive into React's useReducer hook and see how we can use it to manage complex state. We first compare useState and useReducer and slowly add on to our reducer function to make it more flexible.
Dan said this way back in 2016, and now that we have React Context and useReducer hook, the use cases of redux is very minimal. In this post, we will create a good old todo list example using Context and useReducer hook.
As we can see we use four times the Comp1 component. So we need to use
useReducerfour times too in order each of the Comp1 instances have its own state.
Now let's see state.js definition for the app component. It is like this:
This file required the same number of refactors as the
useStateimplementation. One crucial advantage is that these refactors were mostly located together: most changes occurred inside the reducer, and the event handlers went largely untouched. For me, this gives
useReducerthe edge over
The React doc recommends
useReducerfor handling complex state values. But to me they are equally powerful. Let me show you how.
React has a vast collection of hooks which makes it easier for the developers to access the props values into various components. In this app, today we will try to understand the functionality of react's useReducer hook.
The useReducer hook simply creates a store to keep track of the application state, you can then create actions to be performed (like add/delete/update) and then call those actions using the dispatch method of useReducer hook.
-> When to useReducer v useState?
The useReducer hook is very similar to the useState hook, it allows you to manage a state and rerender the component whenever your state changes, It accepts a reducer and an initial state (like the example above) and returns a new version of the state and a dispatch method based on the action performed in the reducer.
This is the second post of my React hooks series. If you haven't read the first one which covers the most basic react hook
useState, check it out here. Today i am going to cover the basics of
Building upon our React hooks introduction from our previous post on understanding React hooks (useState and useEffect), we will look at the useReducer hook in this post. useReducer hook can be an alternative to useState (in fact, useState uses useReducer internally). Before getting into how to use the useReducer hook, we should understand what is meant by a reducer.
The React useReducer hook is a very good alternative to useState when you need to manage complex states with multiple values. In this tutorial, you will learn about this React hook. You will learn about how useReducer hook works. You will also learn how to use it to manage state.
This blog post takes by granted that you are aware of
useReducerlogic and the basics regarding TypeScript.
Well, yes! useState does the job pretty well.
the useState hook is limited in cases where a component needs a complex state structure and proper sync with the tree. useReducer when combined with useContext hook could behave very similarly to Redux pattern and sometimes might be a better approach for global state management instead of other unofficial libraries such as Redux.
As a matter of fact, the useReducer's API itself was used to create a simpler useState hook for state management.
Delivered in React 16.8
useReducerhook allows you to manage complex state logic in React Applications. The
useReducerhook is an alternative for the
useStatehook and, combined with other interesting React’s feature called
Context, helps manage state efficiently.
As stated in the paragraph above, the
useReducerhook should be opted in when the logic behind your state is a bit more complex or depends on the previous state.
Has anyone who's using useReducer checked the render method after each dispatch ?? If not make a console in the JSX and check in development mode
So you finally start your React journey or you're just converting your apps to use functional components and you come across the
useReducerhook but can't really wrap your head around it? I'll show you how in few minutes. Read on...
Managing state in React is one of the main issues you'll be facing while developing React websites.
useStateis of course the most common way to create and manage state in (functional) React components. But do you know that
useReducercan be a very powerful alternative?
If you have used Redux before, you would be aware of the concept of middlewares. Now that useReducer has become a commonly used react hook, we might want to replicate the idea of middleware for the useReducer hook as well.
I was having trouble to understand
useReducerbecause I don't have Redux background. So I wrote this article to explain it to myself, and I hope it can help you as well.
Now this is an update of our
the structure of the
Reducerfunction has been created and and an
initialStateobject as well .
useReducerhook returns two values , a
Managing data access and state management becomes an increasing challenge as projects grow. The responsibilities of loading, updating and managing data in UI components can make UI code complex and unmanageable. The most common pattern for state management in a react app is through react-redux. React's useContext and useReducer is an another approach to managing application state. (There is a comparison of react-redux with useContext and useReducer in the Resources section at the end of this document.)
In this post we will be using a combination of the
useReducerhook and React Context to build our example app, as well as a quick detour to take a look at a library called React Tracked.
useReduceris great when the states get more complex than a simple value. rescript-react
useReduceris even better with ReScript's variants.
Today we will learn how to use React Context API to share values across our application and how to use useReducer hook to manage our states within our project.
A modo de practica decidi hacer la tipica Todo App pero usando funciones reducer y el hook useReducer de React para una manipulacion más estructurada del estado. Asi mismo, use Taildwindcss para darle estilos personalizados y la API de Local Storage para persistencia de datos en el navagador.
useReducer: useReducer is like the Array.prototype.reduce method in vanilla JS. The difference is that reduce method takes a reducer function and initialValue but useReducer takes the reducer function and initialState as the second parameter. Reduce method returns a single value but useReducer returns a tuple [newState, dispatch]
In this post I'll explain the usage of useReducer hook with the help of other hooks, such as useEffect, useMemo, useRef, and useState to manage the complex UI state without using the redux. This post assumes that you all know the basics of hooks and how to use them. If you have not used it before I recommend you all to read the official documentation for getting started.
Are you writing complex functions on useState? You should probably use useReducer instead.
Happy React useReducer coding!