example.js

import { iff } from './globalUtils';

function someRenderFunction() {
  return (
    <div className="otsPropertyForm">
      {iff(showTeamList, () => (
        <FormSection>
          <FormHeading>Select a Team:</FormHeading>
          <ListBox items={teamItems} value={teamId} onChange={this._onTeamListChange} />
        </FormSection>
      ))}
      {iff(showPlayList, () => (
        <FormSection>
          <FormHeading>Select a Play:</FormHeading>
          <ListBox items={playList} value={playId} onChange={this._onPlayListChange} height={300} />
        </FormSection>
      ))}
      <FormSection>
        <FormHeading>Select a Theme:</FormHeading>
        <ListBox items={themeItems} value={dark} onChange={this._onThemeListChange} />
      </FormSection>
    </div>
  );
}

globalUtils.js

/**
* Calls the callback and returns its result if the expression is truthy
*
* @param  {string}   expression
* @param  {Function} callback
* @return {variant}              Value of callback() if expression is true. Otherwise 'undefined'
*/
export function iff(expression, callback) {
  if (expression) {
    return callback();
  }
  return void 0;
}