title: iframe: get active iframe
body: <p>I have a page with multiple iframes, at a time one one iframe is active, and i would like to know which iframe is active currently.</p>
  
  <p>I tried <code>document.activeElement.id</code>, but it gives correct result only when I click on page some where. </p>
  
  <p>I tried <a href="https://stackoverflow.com/questions/25420219/find-focused-element-in-document-with-many-iframes">this</a> also but not giving me active iframe id.</p>
  
  <p>Do you know any javascript/jquery api to know active iframe id.</p>