render() {
    const { collection, fields, widgetFor } = this.props;
    if (!collection || !fields) {
      return null;
    }
    return (
      <PreviewContainer>
        {fields.filter(isVisible).map(field => (
          <div key={field.get('name')}>{widgetFor(field.get('name'))}</div>
        ))}
      </PreviewContainer>
    );
  }
Use a stateful component so that child components can effectively utilize
`shouldComponentUpdate`.