title: Correct way to check if any object is a SyntheticEvent?
body: <p>What is the best way to check if a given object of any kind is a <a href="https://facebook.github.io/react/docs/events.html" rel="noreferrer">SyntheticEvent</a>?</p>
  
  <p>Currently, I'm peering into the internals:</p>
  
  <pre><code>if (obj.nativeEvent ) {
      // 100% sure...with this version of React
  }
  </code></pre>
  
  <p>What is a more idiomatic (or at least future-proof) way of doing this?</p>