insomnia/app/ui/components/base/modal-header.js

import React, {PropTypes, PureComponent} from 'react';
import classnames from 'classnames';

class ModalHeader extends PureComponent {
  render () {
    const {hideCloseButton, className, children} = this.props;
    let closeButton = null;

    if (!hideCloseButton) {
      closeButton = (
        <button type="button" className="btn btn--compact modal__close-btn" data-close-modal="true">
          <i className="fa fa-times"/>
        </button>
      );
    }

    return (
      <div className={classnames('modal__header', className)}>
        <div className="modal__header__children">
          {children}
        </div>
        {closeButton}
      </div>
    );
  }
}

ModalHeader.propTypes = {
  // Required
  children: PropTypes.node.isRequired,

  // Optional
  hideCloseButton: PropTypes.bool,
  className: PropTypes.string
};

export default ModalHeader;