react.dev/index.md

---
layout: page
title: A JavaScript library for building user interfaces
id: home
---
<section class="light home-section">
  <div class="marketing-row">
    <div class="marketing-col">
      <h3>Declarative</h3>
      <p>
        React uses a declarative paradigm that makes it easier to reason about
        your application.
      </p>
    </div>
    <div class="marketing-col">
      <h3>Efficient</h3>
      <p>
        React minimizes interactions with the DOM by using a mock representation
        of the DOM.
      </p>
    </div>
    <div class="marketing-col">
      <h3>Flexible</h3>
      <p>
        React works with the libraries and frameworks that you already know.
      </p>
    </div>
  </div>
</section>
<hr class="home-divider" />
<section class="home-section">
  <div id="examples">
    <div class="example">
      <h3>A Simple Component</h3>
      <p>
        React components implement a `render()` method that takes input data and
        returns what to display. This example constructs the component using an
        XML-like syntax called JSX. Input data is passed to the component as XML
        attributes, and `render()` accesses this data via `this.props`.
      </p>
      <div id="helloExample"></div>
    </div>
    <div class="example">
      <h3>A Stateful Component</h3>
      <p>
        In addition to taking data from its creator (accessed via `this.props`),
        a component can maintain internal state data (accessed via
        `this.state`). When a component's state data changes, the rendered
        markup will be updated by re-invoking `render()`.
      </p>
      <div id="timerExample"></div>
    </div>
    <div class="example">
      <h3>An Application</h3>
      <p>
        Using properties and state, we can put together a small Todo
        application. React provides an interface to the DOM via `refs`. Although
        event handlers appear to be rendered inline, they will be
        collected and implemented using event delegation.
      </p>
      <div id="todoExample"></div>
    </div>
    <div class="example">
      <h3>A Component Using External Plugins</h3>
      <p>
        React is flexible and provides hooks that allow you to interface with
        other libraries and frameworks. This example uses Showdown, an external
        Markdown library, to convert the textarea's value in real-time.
      </p>
      <div id="markdownExample"></div>
    </div>
  </div>
  <script type="text/javascript" src="js/examples/hello.js"></script>
  <script type="text/javascript" src="js/examples/timer.js"></script>
  <script type="text/javascript" src="js/examples/todo.js"></script>
  <script type="text/javascript" src="js/examples/markdown.js"></script>
</section>
<hr class="home-divider" />
<section class="home-bottom-section">
  <div class="buttons-unit">
    <a href="docs/getting-started.html" class="button">Get Started</a>
    <a href="downloads.html" class="button">Download React v{{site.react_version}}</a>
  </div>
</section>