title: How to reach 3rd Party Dom and interact with React
body: <p>I have a react app which is loading an external script which adds a header to my website.</p>
  
  <p>This Header is then added to top of my page and its just pure javascript and html.</p>
  
  <p>But it falls outside of my react app which is right below this header.</p>
  
  <p>But I wish to add certain pieces of information to this 3rd party header from my react redux state.</p>
  
  <p>How can I interact with this 3party div placed on my page from React ?</p>
  
  <p>I.e. my current react render</p>
  
  <pre><code>ReactDOM.render(
      &lt;Provider store={store}&gt;
              &lt;Router history={browserHistory}&gt;{routes(store, intl)}&lt;/Router&gt;
      &lt;/Provider&gt;,
      document.getElementById('app')
  );
  </code></pre>
  
  <p>and app html is something like</p>
  
  <pre><code>&lt;body&gt;
   &lt;header&gt;Something I want to change with redux data&lt;/header&gt;
   &lt;div id="app"&gt;&lt;div&gt;
  &lt;body&gt;
  </code></pre>