danawoodman/0-react-hello-world.md

## 0-react-hello-world.md

      
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              0-react-hello-world.md
            
          
    React "Hello World" Examples

Below are a small collection of React examples to get anyone started using React. They progress from simpler to more complex/full featured.
They will hopefully get you over the initial learning curve of the hard parts of React (JSX, props vs. state, lifecycle events, etc).
Usage

You will want to create an index.html file and copy/paste the contents of 1-base.html and then create a scripts.js file and copy/paste the contents of one of the examples into it.
Serving the examples

You will need to serve these examples using HTTP. You cannot just open the HTML files in a web browser. The easiest way to do this on Linux/OSX is the Python web server:
python -m SimpleHTTPServer 8000
As I don't use windows, I can't really help but check out this article on StackOverflow.
Going Further


React documentation
Flux architecture using Reflux (see this blog post for more)
React routing with react-router
I'd recommend checking out Babel and WebPack for your build tooling setup.
My other Gist on using React + Reflux + WebSockets
Redux is a great library for FLUX as well and seems to becoming the defacto standard in React-land.

Contribute

See things that should be added, improved or clarified? Let me know in the comments!
Updates

April 24, 2016:

Updating to use ReactDOM
Fixing various typos (thanks commenters for pointing them out!)
Update to use newest React
Use Babel instead of JSXTranformer


## 1-base.html
<!DOCTYPE HTML>
<html>
  <head>
    <meta charset="utf-8">
    <title>React Hello World</title>
  </head>
  <body>

    <!--
    The recommended approach in React is to use a container
    dive to load your react code into, rather than using `document.body`.

    This can be any element or tag name, just don't use `document.body`
    if you can avoid it.
    -->
    <div id='root'></div>

    <!--
    For ease of use, we are including the React, ReactDOM and Babel CDN
    builds to make getting started as fast as possible.

    In production, you'll want to instead look at using something
    like Gulp, Grunt or WebPack (my personal recommendation)
    to compile JSX into JavaScript. Also, check out:
    http://facebook.github.io/react/docs/tooling-integration.html
    -->
    <script src="https://fb.me/react-15.0.1.js"></script>
    <script src="https://fb.me/react-dom-15.0.1.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.23/browser.min.js"></script>

    <!--
    This is where you link to your React code. Can be .js or .jsx
    extension, doesn't really matter.
    -->
    <script src="scripts.js" type="text/babel"></script>
  </body>
</html>

## 2-basic.js
/*
The simplist React component ever.

It just renders an H1 tag into the body of the page. Since
JSX is basically just HTML, you can use any valid tag you want.
*/

ReactDOM.render(<h1>Hello World</h1>, document.getElementById('root'));

## 3-simple-component.js
/*
Creating a component

The most simple component has a `render` method that returns some
JSX. `props` are attributes that are passed into the component
when you instantiate it.

One caveat is that `render` must return a single parent element;
you can't return multiple adjacent JSX tags but must wrap them
in one parent element.
*/

var HelloMessage = React.createClass({
  render: function () {
    return <h1>Hello {this.props.message}!</h1>;
  }
});

ReactDOM.render(<HelloMessage message="World" />, document.getElementById('root'));

## 4-internal-state.js
/*
Managing internal state

Sets the intial state of the component and then,
when a link is clicked, updates the state.

When the state updates, the component intelligently
and efficiently re-renders.

Note that the `onClick` is the same as the JavaScript
`onClick` event handler. There are many common browser
events that are supported by React. See them all at:
http://facebook.github.io/react/docs/events.html
*/

var ToggleText = React.createClass({
  getInitialState: function () {
    return {
      showDefault: true
    }
  },

  toggle: function (e) {
    // Prevent following the link.
    e.preventDefault();

    // Invert the chosen default.
    // This will trigger an intelligent re-render of the component.
    this.setState({ showDefault: !this.state.showDefault })
  },

  render: function () {
    // Default to the default message.
    var message = this.props.default;

    // If toggled, show the alternate message.
    if (!this.state.showDefault) {
      message = this.props.alt;
    }

    return (
      <div>
        <h1>Hello {message}!</h1>
        <a href="" onClick={this.toggle}>Toggle</a>
      </div>
    );
  }
});

ReactDOM.render(<ToggleText default="World" alt="Mars" />, document.getElementById('root'));

## 5-combining-components.js
/*
Combining components together

The most fundamental and useful part of React is that
you can create any number of components and nest them
just like you would any HTML tag. You pass down data
to your components from parent components in a one-way
data flow.

Note: If you use something like Flux/Reflux you have a bit
power when it comes to data storage and event handling.
Using a Flux-like framework with React is very helpful.
*/

var ProductItem = React.createClass({
  render: function () {
    return (
      <tr>
        <td>{this.props.name}</td>
        <td>{this.props.price}</td>
      </tr>
    );
  }
});

var ProductList = React.createClass({
  render: function () {
    var products = this.props.products.map(function (product, index) {
      return (
        <ProductItem
          key={index}
          name={product.name}
          price={product.price}
        />
      );
    });

    return (
      <table>
        {products}
      </table>
    );
  }
});

// Could come from an API, LocalStorage, another component, etc...
var products = [
  { name: 'Toast', price: 1499 },
  { name: 'Bacon', price: 3245 },
  { name: 'Coffee', price: 300 }
];

ReactDOM.render(<ProductList products={products} />, document.getElementById('root'));

## 6-whole-shebang.js
/*
Whole Shebang

This example shows most of the commonly used React functionality including:

- Component lifecycle events
- Mixins
- Default props
- Prop validation
- Looping
- DOM refs
- Browser events

See more here lifecycle events here:
http://facebook.github.io/react/docs/component-specs.html

This is by no means how you should write React components, it is just meant to illustrate various features of React.
*/

/*
Mixins are just objects with properties that are merged with the compoent
they are included in.

See: http://facebook.github.io/react/docs/reusable-components.html#mixins
*/
var MyMixin = {
  queryAPIorSomething: function (url, options, successCallback) {
    // Do some API magic here...
  },

  // This does not overwrite the components
  // `componentWillUnmount` method but will
  // be called along side it.
  componetWillUnmount: function () {
    // Abor XHR request or something else...
  }
};


var WholeShebang = React.createClass({
  mixins: [MyMixin],

  propTypes: {
    // This will log a message on the console if
    // items is not defined or if the wrong type
    // is supplied.
    items: React.PropTypes.array.isRequired,

    // This will only log if the type is wrong.
    prefix: React.PropTypes.string,
  },

  // Sane defaults for your component...
  getDefaultProps: function () {
    return {
      prefix: 'Hello'
    }
  },

  getInitialState: function () {
    return {
      showDefault: false,
    }
  },

  componentWillMount: function () {
    // Here you could setState, fetch data from a server or something else...
    this.queryAPIorSomething('path/to/api.json', {} , function (data) {
      this.setState({ data: data });
    }.bind(this));
  },

  componentDidMount: function () {
    // You now have access to the DOM:
    console.log(ReactDOM.findDOMNode(this).innerHTML);

    // ... or to component references:
    console.log(this.refs.foobar.innerHTML);
  },

  componentWillUpdate: function () {
    console.log('component about to update!');
  },

  componentDidUpdate: function () {
    console.log('component updated!');
    // DOM is available here...
  },

  componentWillUnmount: function () {
    // Use this to tear down any event listeners
    // or do other cleanup before the compoennt is
    // destroyed.
    console.log('component will unmount!');
  },

  shouldComponentUpdate: function () {
    // This is called when state/props changed and is
    // an opportunity where you can return false if
    // you don't want the component to update for
    // some reason.
    return true;
  },

  toggle: function (e) {
    // Prevent following the link.
    e.preventDefault();

    // Invert the chosen default.
    // This will trigger an intelligent re-render of the component.
    this.setState({ showDefault: !this.state.showDefault })
  },

  render: function () {
    var items = this.props.items.map(function (item, index) {
      // Any time you construct a list of elements or components,
      // you need to set the `key` so React can more easily work
      // with the DOM.
      return <li key={index}>{item}</li>;
    });

    return (
      <div>
        <span ref="foobar">
          Show default: {this.state.showDefault ? 'True' : 'False'}
        </span>
        <ul>
          {items}
        </ul>
        <a href="" onClick={this.toggle}>Toggle</a>
    </div>
    );
  }
});

ReactDOM.render(
  <WholeShebang items={['Bob', 'Mary', 'Sally']} />,
  document.querySelector('.some-tag') // use other selectors, jQuery or something else to find your target on the page if you want
);
	<!DOCTYPE HTML>
	<html>
	<head>
	<meta charset="utf-8">
	<title>React Hello World</title>
	</head>
	<body>

	<!--
	The recommended approach in React is to use a container
	dive to load your react code into, rather than using `document.body`.

	This can be any element or tag name, just don't use `document.body`
	if you can avoid it.
	-->
	<div id='root'></div>

	<!--
	For ease of use, we are including the React, ReactDOM and Babel CDN
	builds to make getting started as fast as possible.

	In production, you'll want to instead look at using something
	like Gulp, Grunt or WebPack (my personal recommendation)
	to compile JSX into JavaScript. Also, check out:
	http://facebook.github.io/react/docs/tooling-integration.html
	-->
	<script src="https://fb.me/react-15.0.1.js"></script>
	<script src="https://fb.me/react-dom-15.0.1.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.23/browser.min.js"></script>

	<!--
	This is where you link to your React code. Can be .js or .jsx
	extension, doesn't really matter.
	-->
	<script src="scripts.js" type="text/babel"></script>
	</body>
	</html>
	/*
	The simplist React component ever.

	It just renders an H1 tag into the body of the page. Since
	JSX is basically just HTML, you can use any valid tag you want.
	*/

	ReactDOM.render(<h1>Hello World</h1>, document.getElementById('root'));
	/*
	Creating a component

	The most simple component has a `render` method that returns some
	JSX. `props` are attributes that are passed into the component
	when you instantiate it.

	One caveat is that `render` must return a single parent element;
	you can't return multiple adjacent JSX tags but must wrap them
	in one parent element.
	*/

	var HelloMessage = React.createClass({
	render: function () {
	return <h1>Hello {this.props.message}!</h1>;
	}
	});

	ReactDOM.render(<HelloMessage message="World" />, document.getElementById('root'));
	/*
	Managing internal state

	Sets the intial state of the component and then,
	when a link is clicked, updates the state.

	When the state updates, the component intelligently
	and efficiently re-renders.

	Note that the `onClick` is the same as the JavaScript
	`onClick` event handler. There are many common browser
	events that are supported by React. See them all at:
	http://facebook.github.io/react/docs/events.html
	*/

	var ToggleText = React.createClass({
	getInitialState: function () {
	return {
	showDefault: true
	}
	},

	toggle: function (e) {
	// Prevent following the link.
	e.preventDefault();

	// Invert the chosen default.
	// This will trigger an intelligent re-render of the component.
	this.setState({ showDefault: !this.state.showDefault })
	},

	render: function () {
	// Default to the default message.
	var message = this.props.default;

	// If toggled, show the alternate message.
	if (!this.state.showDefault) {
	message = this.props.alt;
	}

	return (
	<div>
	<h1>Hello {message}!</h1>
	<a href="" onClick={this.toggle}>Toggle</a>
	</div>
	);
	}
	});

	ReactDOM.render(<ToggleText default="World" alt="Mars" />, document.getElementById('root'));
	/*
	Combining components together

	The most fundamental and useful part of React is that
	you can create any number of components and nest them
	just like you would any HTML tag. You pass down data
	to your components from parent components in a one-way
	data flow.

	Note: If you use something like Flux/Reflux you have a bit
	power when it comes to data storage and event handling.
	Using a Flux-like framework with React is very helpful.
	*/

	var ProductItem = React.createClass({
	render: function () {
	return (
	<tr>
	<td>{this.props.name}</td>
	<td>{this.props.price}</td>
	</tr>
	);
	}
	});

	var ProductList = React.createClass({
	render: function () {
	var products = this.props.products.map(function (product, index) {
	return (
	<ProductItem
	key={index}
	name={product.name}
	price={product.price}
	/>
	);
	});

	return (
	<table>
	{products}
	</table>
	);
	}
	});

	// Could come from an API, LocalStorage, another component, etc...
	var products = [
	{ name: 'Toast', price: 1499 },
	{ name: 'Bacon', price: 3245 },
	{ name: 'Coffee', price: 300 }
	];

	ReactDOM.render(<ProductList products={products} />, document.getElementById('root'));
	/*
	Whole Shebang

	This example shows most of the commonly used React functionality including:

	- Component lifecycle events
	- Mixins
	- Default props
	- Prop validation
	- Looping
	- DOM refs
	- Browser events

	See more here lifecycle events here:
	http://facebook.github.io/react/docs/component-specs.html

	This is by no means how you should write React components, it is just meant to illustrate various features of React.
	*/

	/*
	Mixins are just objects with properties that are merged with the compoent
	they are included in.

	See: http://facebook.github.io/react/docs/reusable-components.html#mixins
	*/
	var MyMixin = {
	queryAPIorSomething: function (url, options, successCallback) {
	// Do some API magic here...
	},

	// This does not overwrite the components
	// `componentWillUnmount` method but will
	// be called along side it.
	componetWillUnmount: function () {
	// Abor XHR request or something else...
	}
	};


	var WholeShebang = React.createClass({
	mixins: [MyMixin],

	propTypes: {
	// This will log a message on the console if
	// items is not defined or if the wrong type
	// is supplied.
	items: React.PropTypes.array.isRequired,

	// This will only log if the type is wrong.
	prefix: React.PropTypes.string,
	},

	// Sane defaults for your component...
	getDefaultProps: function () {
	return {
	prefix: 'Hello'
	}
	},

	getInitialState: function () {
	return {
	showDefault: false,
	}
	},

	componentWillMount: function () {
	// Here you could setState, fetch data from a server or something else...
	this.queryAPIorSomething('path/to/api.json', {} , function (data) {
	this.setState({ data: data });
	}.bind(this));
	},

	componentDidMount: function () {
	// You now have access to the DOM:
	console.log(ReactDOM.findDOMNode(this).innerHTML);

	// ... or to component references:
	console.log(this.refs.foobar.innerHTML);
	},

	componentWillUpdate: function () {
	console.log('component about to update!');
	},

	componentDidUpdate: function () {
	console.log('component updated!');
	// DOM is available here...
	},

	componentWillUnmount: function () {
	// Use this to tear down any event listeners
	// or do other cleanup before the compoennt is
	// destroyed.
	console.log('component will unmount!');
	},

	shouldComponentUpdate: function () {
	// This is called when state/props changed and is
	// an opportunity where you can return false if
	// you don't want the component to update for
	// some reason.
	return true;
	},

	toggle: function (e) {
	// Prevent following the link.
	e.preventDefault();

	// Invert the chosen default.
	// This will trigger an intelligent re-render of the component.
	this.setState({ showDefault: !this.state.showDefault })
	},

	render: function () {
	var items = this.props.items.map(function (item, index) {
	// Any time you construct a list of elements or components,
	// you need to set the `key` so React can more easily work
	// with the DOM.
	return <li key={index}>{item}</li>;
	});

	return (
	<div>
	<span ref="foobar">
	Show default: {this.state.showDefault ? 'True' : 'False'}
	</span>
	<ul>
	{items}
	</ul>
	<a href="" onClick={this.toggle}>Toggle</a>
	</div>
	);
	}
	});

	ReactDOM.render(
	<WholeShebang items={['Bob', 'Mary', 'Sally']} />,
	document.querySelector('.some-tag') // use other selectors, jQuery or something else to find your target on the page if you want
	);