static-cms/src/components/Widgets/ImagePreview.js

import React, { PropTypes } from 'react';

export default function ImagePreview({ value, getMedia }) {
  return <span>
    {value ? <img src={getMedia(value)}/> : null}
  </span>;
}

ImagePreview.propTypes = {
  getMedia: PropTypes.func.isRequired,
  value: PropTypes.node,
};