title: What library stackoverflow forms use to display error (Bootstrap popover for error help-block)
body: <p>I have a form and I want to display validation error messages. right now I use bootstrap has-error and help-block to show validations. but I really like how error messages are displayed in Stackoverflow's ask Questions Form. Is there a js/css library that is used to show these messages or is this something built by stackoverflow, in either case how can I create something like this in my forms (preferably an extension to bootstrap).</p>
  
  <p><a href="https://i.stack.imgur.com/gl8sx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gl8sx.png" alt="enter image description here"></a></p>