React

The library for web and native user interfaces

Create user interfaces from components

React lets you build user interfaces out of individual pieces called components. Create your own React components like Thumbnail, LikeButton, and Video. Then combine them into entire screens, pages, and apps.

Video.js

function Video({ video }) {
  return (
    <div>
      <Thumbnail video={video} />
      <a href={video.url}>
        <h3>{video.title}</h3>
        <p>{video.description}</p>
      </a>
      <LikeButton video={video} />
    </div>
  );
}

My video

Video description

Whether you work on your own or with thousands of other developers, using React feels the same. It is designed to let you seamlessly combine components written by independent people, teams, and organizations.

Write components with code and markup

React components are JavaScript functions. Want to show some content conditionally? Use an if statement. Displaying a list? Try array map(). Learning React is learning programming.

VideoList.js

function VideoList({ videos, emptyHeading }) {
  const count = videos.length;
  let heading = emptyHeading;
  if (count > 0) {
    const noun = count > 1 ? 'Videos' : 'Video';
    heading = count + ' ' + noun;
  }
  return (
    <section>
      <h2>{heading}</h2>
      {videos.map(video =>
        <Video key={video.id} video={video} />
      )}
    </section>
  );
}

3 Videos

First video

Video description

Second video

Video description

Third video

Video description

This markup syntax is called JSX. It is a JavaScript syntax extension popularized by React. Putting JSX markup close to related rendering logic makes React components easy to create, maintain, and delete.

Add interactivity wherever you need it

React components receive data and return what should appear on the screen. You can pass them new data in response to an interaction, like when the user types into an input. React will then update the screen to match the new data.

SearchableVideoList.js

import { useState } from 'react';

function SearchableVideoList({ videos }) {
  const [searchText, setSearchText] = useState('');
  const foundVideos = filterVideos(videos, searchText);
  return (
    <>
      <SearchInput
        value={searchText}
        onChange={newText => setSearchText(newText)} />