React lets you create components, reusable UI elements for your app. In a React app, every piece of UI is a component. React components are regular JavaScript functions except: Their names always begin with a capital letter. They return JSX markup.

Creating and nesting components . React apps are made out of components. A component is a piece of the UI (user interface) that has its own logic and appearance. A component can be as small as a button, or as large as an entire page. React components are …

Call createElement to create a React element with the given type, props, and children.

Component is the base class for the React components defined as JavaScript classes. Class components are still supported by React, but we don’t recommend using them in new code.

App.js. The code in App.js creates a component. In React, a component is a piece of reusable code that represents a part of a user interface. Components are used to render, manage, and update the UI elements in your application. Let’s look …

You can move a component in three steps: Make a new JS file to put the components in. Export your function component from that file (using either default or named exports). Import it in the file where you’ll use the component (using the corresponding technique for importing default or named exports).

In general, if some information is needed by distant components in different parts of the tree, it’s a good indication that context will help you. Recap. Context lets a component provide some information to the entire tree below it. To pass context: Create and export it with export const MyContext = createContext(defaultValue).

Next.js’s App Router bundler fully implements the official React Server Components specification. This lets you mix build-time, server-only, and interactive components in a single React tree. For example, you can write a server-only React component as an async function that reads from a database or from a file. Then you can pass data down ...

Every parent component can pass some information to its child components by giving them props. Props might remind you of HTML attributes, but you can pass any JavaScript value through them, including objects, arrays, and functions.

Declaring a ref in a class component To declare a ref inside a class component, call createRef and assign its result to a class field: import { Component , createRef } from 'react' ;