:focus Selector

focus ( ) version added: 1.6

Description: Selects element if it is currently focused.

As with other pseudo-class selectors (those that begin with a ":"), it is recommended to precede :focus with a tag name or some other selector; otherwise, the universal selector ( "*" ) is implied. In other words, the bare $( ":focus" ) is equivalent to $( "*:focus" ). If you are looking for the currently focused element, $( document.activeElement ) will retrieve it without having to search the whole DOM tree.

Examples:

Example: Adds the focused class to whatever element has focus 

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>css demo</title>

  <style>

  .focused {
    background: #abcdef;
  }

  </style>

  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
  

<div id="content">
  <input tabIndex="1">
  <input tabIndex="2">
  <select tabIndex="3">
    <option>select menu</option>
  </select>
  <div tabIndex="4">
    a div
  </div>
</div>

<script>

$( "#content" ).delegate( "*", "focus blur", function() {
  var elem = $( this );
  setTimeout(function() {
    elem.toggleClass( "focused", elem.is( ":focus" ) );
  }, 0 );
});

</script>

  
</body>
</html>

Demo: