React is a JavaScript library for building user interfaces.

• Declarative: React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code more predictable, simpler to understand, and easier to debug.
• Component-Based: Build encapsulated components that manage their own state, then compose them to make complex UIs. Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep state out of the DOM.
• Learn Once, Write Anywhere: We don't make assumptions about the rest of your technology stack, so you can develop new features in React without rewriting existing code. React can also render on the server using Node and power mobile apps using React Native.

Learn how to use React in your own project.

We have several examples on the website. Here is the first one to get you started:

class HelloMessage extends React.Component {
  render() {
    return <div>Hello {this.props.name}</div>;
  }
}

ReactDOM.render(
  <HelloMessage name="John" />,
  document.getElementById('container')
);

This example will render "Hello John" into a container on the page.

You'll notice that we used an HTML-like syntax; we call it JSX. JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML. A simple transform is included with React that allows converting JSX into native JavaScript for browsers to digest.

The fastest way to get started is to serve JavaScript from a CDN. We're using unpkg below but React is also available on cdnjs and jsdelivr:

<!-- The core React library -->
<script src="https://unpkg.com/[email protected]/dist/react.js"></script>
<!-- The ReactDOM Library -->
<script src="https://unpkg.com/[email protected]/dist/react-dom.js"></script>

We've also built a starter kit which might be useful if this is your first time using React. It includes a webpage with an example of using React with live code.

If you'd like to use bower, it's as easy as:

bower install --save react

And it's just as easy with npm:

npm i --save react

The main purpose of this repository is to continue to evolve React core, making it faster and easier to use. Development of React happens in the open on GitHub, and we are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving React.

Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.

Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React.

To help you get your feet wet and get you familiar with our contribution process, we have a list of good first bugs that contain bugs which are fairly easy to fix. This is a great place to get started.

React is BSD licensed. We also provide an additional patent grant.

React documentation is Creative Commons licensed.

Examples provided in this repository and in the documentation are separately licensed.

See the Troubleshooting Guide