title: How to detect when a tab is focused or not in Chrome with Javascript?
body: <p>I need to know if the user is currently viewing a tab or not in Google Chrome. I tried to use the events blur and focus binded to the window, but only the blur seems to be working correctly.</p>
  
  <pre><code>window.addEventListener('focus', function() {
    document.title = 'focused';
  });
  
  window.addEventListener('blur', function() {
    document.title = 'not focused';
  });
  </code></pre>
  
  <p>The focus event works weird, only sometimes. If I switch to another tab and back, focus event won't activate. But if I click on the address bar and then back on the page, it will. Or if I switch to another program and then back to Chrome it will activate if the tab is currently focused.</p>