Expand / Collapse text toggling for Bootstrap3

collapse-toggle.js

$(function () {
  var active = true;
  $('#expand-btn').click(function() {
    if (active) {
      active = false;
      $('.collapse:not(.in)').collapse('show');
      $('.panel-header').attr('data-toggle', 'collapse');
      $(this).text('Collapse all sections');
    } else {
      active = true;
      $('.collapse').collapse('hide');
      $('.panel-header').attr('data-toggle', 'collapse');
      $(this).text('Expand all sections');
    }
  });
});