gistfile1.txt

// fix for keyboard focus states on scroll position or timed based popup implementations
//
// forces the focus back to the element that was focused prior to popup open
// fixes focus bug when faking a click on existing element to bring up a modal window
// fixes accessibility issue where the user's focus was changed when the popup shows
//

/**
 * Gets keyboard-focusable elements within a specified element
 * @param {HTMLElement} [element=document] element
 * @returns {Array}
 */
function getKeyboardFocusableElements () {
  return document.querySelectorAll(
    'a, button, input, textarea, select, details,[tabindex]:not([tabindex="-1"])'
  );
}

// implementation below fires on bootstrap modal close event -- change bootstrap event out for whatever event your modal fires on close
$('#modal').on('hidden.bs.modal', function () {

  // catches an empty focus element (e.g., user hasn't interacted with page via keyboard yet)
  if ( prePopupFocusedElement === document.body ) {
    document.body.tabIndex = 0;
    document.body.focus({preventScroll: true});
  } else {
    prePopupFocusedElement.focus();
  }