OffFocus.jsx

class OffFocus extends React.Component {
    constructor(){
        super()
    
        const handler = e => {
            if(
                this.state.focused 
            && 
                e.target.nodeType 
            && 
                !this.refs.wrapper.contains(e.target)
            )
                this.props.callback()
        }
      
        this.listener = [
            'focus',
            handler,
            true,
        ]
    
        this.state = {
            focused : false,
        }
    }
  
    componentDidMount(){
        addEventListener(...this.listener)
    }
  
    componentWillUnmount(){
        removeEventListener(...this.listener)
    }

    render = () =>
        <div ref='wrapper'>
            {this.children}
        </div>
}