react context api

Now we reached the part where you ask me "why should I use this context api instead of redux, that is far more stable and is adopted by a large portion of the community? From what I have learned with the few things I studied about it, I imagine that this is not going to kill redux. PS. How it works. Create a folder under your app root named contexts (not required. We want to build a “theme toggler” component which toggles between light mode and dark mode for our React app. A theme might be implemented using Context - for example, on this site I have Context serving three themes: dark mode, light mode, and MS-DOS mode (on the 404 page).In this simple example, I'll use a logged in user. To use this new context API you need to be familiar with three things: Tip: Personally I like to create a separated file for my contexts, but that's up to you. For functional components, you'll use useContext, such as in the example below. The React.createContext method also returns a consumer component when it is called. I'll wrap the entire App component in the Provider. How do I implement Context API in my app?" There are alternatives, such as Redux, a library for managing the state of the application, but unlike to the Context API, it requires a lot of configuration to get started. I publish guides and tutorials about modern JavaScript, design, and programming. The useState hook will return the current value of the theme and a function which we can use to update the theme. Introducing the context. : This is my first post, so I'm accepting constructive criticism, PS2. The ChildComponent had nothing to do with the theme props but was just used as an intermediary. The first element is our state variable and the second element is a function in which we can use the update the value of the state variable. Do you spend a lot of time reproducing errors in your apps? We passed an array to the React.createContext function. More about React Context API was created to solve a major problem that almost every application has faced - Prop Drilling. With release of React 16.3, React is urging us to migrate to the new Context API. Subscribe and get the Smart Interface Design Checklists PDF delivered to your inbox. According to the React documentation: For a more in-depth definition, it provides a way for you to make particular data available to all components throughout the component tree no matter how deeply nested that component may be. Here is what consuming our ThemeContext with a functional component would look like: As you can see, all we had to do was use our useContext hook with our ThemeContext passed in as an argument. In the above example, this.context was referenced in the render() method. A component that uses it is always re-rendered when the Context value changes: The Context API in React is a way to create and share a global state throughout the application, which is very useful for eliminating the need for props drilling. We provide world-class security for your customers during login, registration, password setup, and any other data touchpoints, and make sure that their data is safe. With Context, every component in the component tree has access to whatever data we decide to put in our context. But what if the number of levels increases to 10, or even 20? We then wrote an onClick event handler for our ThemeToggler. mdamien (Damien) November 7, 2020, 11:39am #1. We can toggle between blue and red themes by using state. It offers us with similar features as redux. When NewContext is viewed in the React DevTools, its name should appear as NameOfContext: The Class.contextType property allows a component to consume the nearest value of a Context object that has been assigned to it. However, Redux has its disadvantages, and that's why it's important to know what Context API gives us that Redux doesn't: Simplicity - When using redux people tend to manage almost all of their state in redux and it causes 2 problems: Using Context API we can define several unrelated contexts (stores) and use each in its proper place in the app. So, let us write the click event handler like so: Now, we want to set the new theme to Red if the current theme is Blue, and vice versa. But enought with the jibber-jabber, let's go to what really matters, how do we use it? The createContext method is used to create a Context object to which components can subscribe. It’s important to note that with Context, components lose much of their independence. If you need the value from Context outside of render, or in a lifecycle method, you'll use it this way. So now, we have written our onClick handler. The color of the h1 element depends on the current theme mode. I am Volodymyr Hudyma React developer with more than 5 years of experience in software development. LogRocket also monitors your app's performance, reporting with metrics like client CPU load, client memory usage, and more. According to the official React documentation, Context provides a way to pass data through the component tree without having to pass props down manually at each level. Remember that definition I showed you guys a little earlier? To create and use a Context, the following steps must be taken: A Context can be created using React.creactContext(defaultValue) function: Then the React component can subscribe to this context and read the current context value from the nearest Provider at the top. Most of the time, the data you have in one component will only be relevant to its children, so passing it in props is more indicative and nicer. Provider is a component that as it's names suggests provides the state to its children. One of the significant advantages of React's one-way data binding is that it's easy to understand - A component passes state to its children. What the Context API is and the problem it solves. It’s going to show a greeting saying “Hello {firstname} {lastname}” and while waiting for the “api” we are going to show a spinner. What is Context API? I mentioned how people overuse Redux, and it also applies to Context API. The most common way to access Context from a class component is via the static contextType. Library: Use a library like Redux or MobX to manage state for you. Our React.createContext will now take an object resembling the result of a useState hook as an argument. React Context API is a way to essentially create global variables that can be passed around in a React app. Still in its early phase React 16.3 Context API can be used as an alternative to the classic state management alternative if your sole purpose of using a state management library is …

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