Example using a class component

class HelloWorldWidget extends React.Component {
  render() {
      return (
          <div>
              Hello World!
          </div>
      );
  }
};

ReactDOM.render(
  <HelloWorldWidget />,
  document.body
);

Example using function component

function HelloWorldWidget() {
  return <div>Hello World!</div>;
}

ReactDOM.render(
  <HelloWorldWidget />,
  document.body
);

Getting started

npx create-react-app my_app

Advantages

• React creates a virtual DOM so that all the components can be re-rendered individually without the need for the whole page to be repainted by the browser

• A user can update a particular content of the page just by re-rendering only that component

• In React, data flows from the owner to the child. You can think of it as "one-way data binding."

• React's view logic means it can quickly render on the server, in the browser or native components

• React can be used in conjunction with frameworks like angular.js and backbone.js

• Separating the declarative view (jsx) and logically making projects easier to read and maintain

Resources:

• Official website
• Getting started
• Awesome React
• JSX Specification
• React conference 2015 videos
• React conference 2016 videos
• React conference 2017 videos
• React conference 2018 videos
• React conference 2019 videos
• CodeSandbox Playground
• DEV’s React community
• Reactiflux on Discord
• Hashnode’s React community
• Reddit’s React community
• ReactJS Program
• TypeScript-React-Starter

Books:

• React.js Essentials
• Mastering React
• ReactJS by Example - Building Modern Web Applications with React
• The Road to learn React
• Fullstack React: The Complete Guide to ReactJS and Friends

Related tags:

• react-router
• react-router-dom
• reactjs-flux
• react-native
• redux
• react-redux
• redux-thunk
• redux-form
• react-router-redux
• reactjs-testutils
• react-dom
• isomorphic-javascript
• react-bootstrap
• redux-saga
• react-dnd
• react-vr
• reason-react
• create-react-app
• react-jsx
• formik
• react-hooks
• react-context
• react-fiber
• material-ui

Official Logo:

Versions:

_{Note: The table below only summarises changes for each version. A comprehensive list of changes for each version can be found here.}