We'll first need an event handler to invoke the mutation. We'll use a click handler on the thumbs-up icon.

In the displayLikes() method on the Quote component (in js/Quote.js), modify the span for the icon to include an onClick event:

  displayLikes() { 
    if (!this.props.relay.variables.showLikes) { 
      return null; 
    } 
    return ( 
      <div> 
        {this.props.quote.likesCount} &nbsp; 
        <span className="glyphicon glyphicon-thumbs-up" 
              onClick={this.thumbsUpClick}></span> 
      </div> 
    ); 
  } 

thumbsUpClick will simply instantiate a mutation class and pass it to Relay.Store.commitUpdate:

  // In js/quote.js Quote component definition 
  thumbsUpClick = () => { 
    Relay.Store.commitUpdate( 
      new ThumbsUpMutation({ 
        quote: this.props.quote 
      }) 
    ) 
  }; 

The instantiated object from...