title: Cross domain popup window with return value
body: <p><strong>This is the setup:</strong></p>
  
  <p>I have two websites on two different domains:</p>
  
  <ul>
  <li><code>www.website1.com</code></li>
  <li><code>www.someotherwebsite.com</code></li>
  </ul>
  
  <p><strong>This is what I want to do:</strong></p>
  
  <ol>
  <li><p>When a user is on <code>www.website1.com</code> and clicks a link, I want a window to popup showing <code>www.someotherwebsite.com</code>.</p></li>
  <li><p>When the user clicks a button in the popup window (showing <em><code>www.someotherwebsite.com</code></em>) I want that window to close and have a value returned.</p></li>
  <li><p>I want the value returned from the popup window to be placed (into a div, or into a javascript call, or someplace accessible such as filling out a form field) on <code>www.website1.com</code>.</p></li>
  </ol>
  
  <p>I hope that makes sense.  I need to use just HTML and Javascript without external libraries.  It also must work on current mainstream browsers (i.e. not be an HTML5 thing).</p>
  
  <p>Thank you in advance for your help.</p>