class CommentList extends React.Component {

  constructor() {

   super();

   this.handleChange = this.handleChange.bind(this);

   this.state = {

    // "DataSource" is some global data source

    comments: DataSource.getComments()

   };

  }

 

  componentDidMount() {

   // Subscribe to changes

   DataSource.addChangeListener(this.handleChange);

  }

 

  componentWillUnmount() {

   // Clean up listener

   DataSource.removeChangeListener(this.handleChange);

  }

 

  handleChange() {

   // Update component state whenever the data source changes

   this.setState({

    comments: DataSource.getComments()

   });

  }

 

  render() {

   return (

    <div>

     {this.state.comments.map((comment) => (

      <Comment comment={comment} key={comment.id} />

     ))}

    </div>

   );

  }

 } 

class BlogPost extends React.Component {

  constructor(props) {

   super(props);

   this.handleChange = this.handleChange.bind(this);

   this.state = {

    blogPost: DataSource.getBlogPost(props.id)

   };

  }

 

  componentDidMount() {

   DataSource.addChangeListener(this.handleChange);

  }

 

  componentWillUnmount() {

   DataSource.removeChangeListener(this.handleChange);

  }

 

  handleChange() {

   this.setState({

    blogPost: DataSource.getBlogPost(this.props.id)

   });

  }

 

  render() {

   return <TextBlock text={this.state.blogPost} />;

  }

 } 

const CommentListWithSubscription = withSubscription(

 CommentList,

 (DataSource) => DataSource.getComments()

);

 

const BlogPostWithSubscription = withSubscription(

 BlogPost,

 (DataSource, props) => DataSource.getBlogPost(props.id)

); 

// This function takes a component...

function withSubscription(WrappedComponent, selectData) {

 // ...and returns another component...

 return class extends React.Component {

  constructor(props) {

   super(props);

   this.handleChange = this.handleChange.bind(this);

   this.state = {

    data: selectData(DataSource, props)

   };

  }

 

  componentDidMount() {

   // ... that takes care of the subscription...

   DataSource.addChangeListener(this.handleChange);

  }

 

  componentWillUnmount() {

   DataSource.removeChangeListener(this.handleChange);

  }

 

  handleChange() {

   this.setState({

    data: selectData(DataSource, this.props)

   });

  }

 

  render() {

   // ... and renders the wrapped component with the fresh data!

   // Notice that we pass through any additional props

   return <WrappedComponent data={this.state.data} {...this.props} />;

  }

 };

} 

function logProps(InputComponent) {

 InputComponent.prototype.componentWillReceiveProps = function(nextProps) {

  console.log('Current props: ', this.props);

  console.log('Next props: ', nextProps);

 };

 // The fact that we're returning the original input is a hint that it has

 // been mutated.

 return InputComponent;

}

 

// EnhancedComponent will log whenever props are received

const EnhancedComponent = logProps(InputComponent); 

function logProps(WrappedComponent) {

 return class extends React.Component {

  componentWillReceiveProps(nextProps) {

   console.log('Current props: ', this.props);

   console.log('Next props: ', nextProps);

  }

  render() {

   // Wraps the input component in a container, without mutating it. Good!

   return <WrappedComponent {...this.props} />;

  }

 }

} 

render() {

 // A new version of EnhancedComponent is created on every render

 // EnhancedComponent1 !== EnhancedComponent2

 const EnhancedComponent = enhance(MyComponent);

 // That causes the entire subtree to unmount/remount each time!

 return <EnhancedComponent />;

} 

// Define a static method

WrappedComponent.staticMethod = function() {/*...*/}

// Now apply an HOC

const EnhancedComponent = enhance(WrappedComponent);

 

// The enhanced component has no static method

typeof EnhancedComponent.staticMethod === 'undefined' // true 

function enhance(WrappedComponent) {

 class Enhance extends React.Component {/*...*/}

 // Must know exactly which method(s) to copy :(

  // 你也能够借助第三方工具

 Enhance.staticMethod = WrappedComponent.staticMethod;

 return Enhance;

}