Question

How to add a class to the textarea’s parent div when clicked or focused?

$(document).ready(function () {  
$('textarea').toggleClass(function() {
  if ($(this).parent().is('.expandingArea')) {
    return $(this).parent().addClass('open');
  } else {
    return $(this).parent().removeClass('open');
  }
});
});

Answer 1

You can just use focus and blur to get this functionality.

$('textarea').focus( function() {
  $(this).parent().addClass('open');
});

$('textarea').blur( function() {
 $(this).parent().removeClass('open');
});

DEMO

Another One