title: How do I implement postMessage() in JavaScript?
body: <p>I need help with the <code>window.postMessage</code> method. I'm trying to post a message to an iframe from the parent window.</p>
  
  <p>The iframe's name and ID is <code>myFrame</code>, and I have tried the following code, with no avail:</p>
  
  <pre><code>document.getElementById('myFrame').contentWindow.postMessage('Hello','*')
  </code></pre>