content: import React, { Component } from 'react';
  import Target from './example4/target';
  import Source from './example4/source';
  
  class Example4 extends Component {
    getTarget = () => this.refs.target;
  
    render() {
      return (
        <div style={{ background: 'red', position: 'relative', padding: '20px' }}>
          <div style={{ height: '600px', background: 'purple' }}>
          </div>
          <Target ref="target"/>
          <Source target={this.getTarget}/>
        </div>
      );
    }
  }
  
  export default Example4;
  