---
title: React.js (v0.14)
category: React
deprecated: true
intro: |
  **Deprecated:** this guide targets an old version of React (v0.14). See the [updated React cheatsheet](react) for new versions.
---

{%raw%}

### Components

```js
var Component = React.createClass({
  render: function () {
    return <div>Hello {this.props.name}</div>;
  }
});
```

```js
ReactDOM.render(<Component name="John" />, document.body);
```
{:.light}

Use the [React.js jsfiddle](http://jsfiddle.net/reactjs/69z2wepo/) to start hacking. (or the unofficial [jsbin](http://jsbin.com/yafixat/edit?js,output))

### Nesting

```js
var UserAvatar  = React.createClass({...});
var UserProfile = React.createClass({...});
```
{:.light}

```js
var Info = React.createClass({
  render() {
    return <div>
      <UserAvatar src={this.props.avatar} />
      <UserProfile username={this.props.username} />
    </div>;
  }
});
```

Nest components to separate concerns. See [multiple components](http://facebook.github.io/react/docs/multiple-components.html).

## States & Properties
{:.center}

### States and props

```html
<MyComponent fullscreen={true} />
```
{:.light}
 
```js
// props
  this.props.fullscreen //=> true

// state
  this.setState({ username: 'rstacruz' });
  this.replaceState({ ... });
  this.state.username //=> 'rstacruz'
```

```js
render: function () {
  return <div className={this.props.fullscreen ? 'full' : ''}>
    Welcome, {this.state.username}
  </div>;
}
```

Use [props](https://facebook.github.io/react/docs/tutorial.html#using-props) (`this.props`) to access parameters passed from the parent.
Use [states](https://facebook.github.io/react/docs/tutorial.html#reactive-state) (`this.state`) to manage dynamic data.

### Setting defaults

```js
React.createClass({
  getInitialState: function () {
    return { comments: [] };
  },

  getDefaultProps: function () {
    return { name: "Hello" };
  }
);
```

Pre-populates `this.state.comments` and `this.props.name`.

## Components

### Component API

```js
ReactDOM.findDOMNode(c)  // 0.14+
React.findDOMNode(c)  // 0.13
c.getDOMNode()        // 0.12 below
```
{:.light}

```js
c.forceUpdate()
c.isMounted()

c.state
c.props

c.setState({ ... })
c.replaceState({ ... })

c.setProps({ ... })       // for deprecation
c.replaceProps({ ... })   // for deprecation

c.refs
```

These are methods available for `Component` instances. See [Component API](http://facebook.github.io/react/docs/component-api.html).

### Component specs

| Method | What |
| ---- | ---- |
| [`render()`](http://facebook.github.io/react/docs/component-specs.html#render) | |
| ---- | ---- |
| [`getInitialState()`](http://facebook.github.io/react/docs/component-specs.html#getinitialstate) | |
| [`getDefaultProps()`](http://facebook.github.io/react/docs/component-specs.html#getdefaultprops) |  |
| ---- | ---- |
| [`mixins: [ ... ]`](http://facebook.github.io/react/docs/component-specs.html#mixins) | Mixins ... [more](#mixins) |
| [`propTypes: { ... }`](http://facebook.github.io/react/docs/component-specs.html#proptypes) | Validation ... [more](#property-validation) |
| [`statics: { ... }`](http://facebook.github.io/react/docs/component-specs.html#statics) | Static methods |
| [`displayName: "..."`](http://facebook.github.io/react/docs/component-specs.html#displayname) | Automatically filled by JSX |
{:.greycode.no-head}

Methods and properties you can override. See [component specs](http://facebook.github.io/react/docs/component-specs.html).

## Lifecycle

### Mounting

| `componentWillMount()` | Before rendering (no DOM yet) |
| `componentDidMount()` | After rendering |
{:.greycode.no-head.lc}

Before initial rendering occurs. Add your DOM stuff on didMount (events, timers, etc). See [reference](http://facebook.github.io/react/docs/component-specs.html#mounting-componentwillmount).

### Updating

| `componentWillReceiveProps`*(newProps={})* | Use `setState()` here |
| `shouldComponentUpdate`*(newProps={}, newState={})* | Skips `render()` if returns false |
| `componentWillUpdate`*(newProps={}, newState={})* | Can't use `setState()` here |
| `componentDidUpdate`*(prevProps={}, prevState={})* | Operate on the DOM here |
{:.greycode.no-head.lc}

Called when parents change properties and `.setState()`. These are not called for initial renders. See [reference](http://facebook.github.io/react/docs/component-specs.html#updating-componentwillreceiveprops).

### Unmounting

| `componentWillUnmount()` | Invoked before DOM removal |
{:.greycode.no-head.lc}

Clear your DOM stuff here (probably done on didMount). See [reference](http://facebook.github.io/react/docs/component-specs.html#unmounting-componentwillunmount).

## Examples

### Example: loading data

```js
React.createClass({
  componentDidMount: function () {
    $.get(this.props.url, function (data) {
      this.setState(data);
    }.bind(this));
  },

  render: function () {
    return <CommentList data={this.state.data} />
  }
});
```

See [initial AJAX data](http://facebook.github.io/react/tips/initial-ajax.html).

## DOM nodes

### References

```html
<input ref="myInput">
```
{:.light}

```js
this.refs.myInput
ReactDOM.findDOMNode(this.refs.myInput).focus()
ReactDOM.findDOMNode(this.refs.myInput).value
```

### DOM Events
Add attributes like `onChange`. See [events](https://facebook.github.io/react/docs/events.html).

```html
<input type="text"
    value={this.state.value}
    onChange={this.handleChange} />
```
{:.light}

```js
handleChange: function(event) {
  this.setState({ value: event.target.value });
}
```

Allows access to DOM nodes. See [References](http://facebook.github.io/react/docs/more-about-refs.html).

### Two-way binding

```html
Email: <input type="text" valueLink={this.linkState('email')} />
```
{:.light}

```js
React.createClass({
  mixins: [React.addons.LinkedStateMixin]
});
```

```js
this.state.email
```

Use [LinkedStateMixin](http://facebook.github.io/react/docs/two-way-binding-helpers.html) for easier two-way binding.

## Property validation

### Basic types

```js
React.createClass({
  propTypes: {
    email:      React.PropTypes.string,
    seats:      React.PropTypes.number,
    settings:   React.PropTypes.object,
    callback:   React.PropTypes.func,
    isClosed:   React.PropTypes.bool,
    any:        React.PropTypes.any,
  }
});
```
Primitive types: `.string`, `.number`, `.func`, and `.bool`. See [propTypes](http://facebook.github.io/react/docs/reusable-components.html#prop-validation).

### Required types

```js
propTypes: {
  requiredFunc:  React.PropTypes.func.isRequired,
  requiredAny:   React.PropTypes.any.isRequired,
```

Add `.isRequired`.

### React elements

```js
propTypes: {
  element:  React.PropTypes.element,  // react element
  node:     React.PropTypes.node,     // num, string, element
                                      // ...or array of those
```

Use `.element`, `.node`.

### Enumerables

```
propTypes: {
  enum:     React.PropTypes.oneOf(['M','F']),  // enum
  union:    React.PropTypes.oneOfType([        // any
              React.PropTypes.string,
              React.PropTypes.number ]),
```

Use `.oneOf`, `.oneOfType`.

### Arrays and objects

```js
propTypes: {
  array:    React.PropTypes.array,
  arrayOf:  React.PropTypes.arrayOf(React.PropTypes.number),
  object:   React.PropTypes.object,
  objectOf: React.PropTypes.objectOf(React.PropTypes.number),

  message:  React.PropTypes.instanceOf(Message),

  object2:  React.PropTypes.shape({
    color:  React.PropTypes.string,
    size:   React.PropTypes.number
  }),
```

Use `.array[Of]`, `.object[Of]`, `.instanceOf`, `.shape`.

### Custom validation

```js
propTypes: {
  customProp: function(props, propName, componentName) {
    if (!/matchme/.test(props[propName])) {
      return new Error('Validation failed!');
    }
  }
}
```

Supply your own function.

## Other features

### Class set

```js
var cx = require('classnames');

render: function() {
  var classes = cx({
    'message': true,
    'message-important': this.props.isImportant,
    'message-read': this.props.isRead
  });

  return <div className={classes}>Great Scott!</div>;
}
```

Manipulate DOM classes with [classnames](https://www.npmjs.org/package/classnames), previously known as `React.addons.classSet`. See [Class set](http://facebook.github.io/react/docs/class-name-manipulation.html).

### Propagating properties

```html
<VideoPlayer src="video.mp4" />
```
{:.light}

```js
var VideoPlayer = React.createClass({
  render: function() {
    /* propagates src="..." down to this sub component */
    return <VideoEmbed {...this.props} controls='false' />;
  }
});
```

See [Transferring props](http://facebook.github.io/react/docs/transferring-props.html).

### Mixins

```js
var SetIntervalMixin = {
  componentWillMount: function() { .. }
}
```
{:.light}

```js
var TickTock = React.createClass({
  mixins: [SetIntervalMixin]
}
```

See [addons](https://facebook.github.io/react/docs/addons.html) for some built-in mixins.

## [Top level API](https://facebook.github.io/react/docs/top-level-api.html)

```js
React.createClass({ ... })

React.isValidElement(c)

ReactDOM.findDOMNode(c) // 0.14+
ReactDOM.render(<Component />, domnode, [callback]) // 0.14+
ReactDOM.unmountComponentAtNode(domnode) // 0.14+

ReactDOMServer.renderToString(<Component />) // 0.14+
ReactDOMServer.renderToStaticMarkup(<Component />) // 0.14+
```

## JSX patterns

### Style shorthand

```js
var style = { backgroundImage: 'url(x.jpg)', height: 10 };
return <div style={style}></div>;
```

See [inline styles](https://facebook.github.io/react/tips/inline-styles.html).

### InnerHTML

```js
function markdownify() { return "<p>...</p>"; }
<div dangerouslySetInnerHTML={{__html: markdownify()}} />
```

See [dangerously set innerHTML](https://facebook.github.io/react/tips/dangerously-set-inner-html.html).

### Lists

```js
var TodoList = React.createClass({
  render: function() {
    function item(itemText) {
      return <li>{itemText}</li>;
    };
    return <ul>{this.props.items.map(item)}</ul>;
  }
});
```

## See also

* [Animations](http://facebook.github.io/react/docs/animation.html)
{%endraw%}