gistfile1.txt

document.addEventListener('DOMContentLoaded', function() {
  setTimeout(function() { default_lettings_button() }, 100 ); // delay execution of defaulting
});

function default_lettings_button()
{
  var checked_department = jQuery('input[name="department"]:checked').val();
  if ( checked_department == 'residential-lettings' )
  {
      toggleActive(document.querySelector('.control-department label[for="department_residential-lettings"]'));
  }
}