Selenium - Focus the next/previous element when the Tab key is not supported

#focus-next.py

JS_TAB_FOCUS = open('tab-focus.js', 'r').read()

# focus the next element
elem_next = driver.execute_scrit(JS_TAB_FOCUS, false)
elem_next.send_keys("abcd")

# focus the previous element
elem_prev = driver.execute_scrit(JS_TAB_FOCUS, true)
elem_prev.click()

tab-focus.js

var backward = arguments[0];
var active = document.activeElement;

var event = document.createEvent('KeyboardEvent');
event.initKeyEvent('keydown', true, true, document.defaultView, false, false, backward, false, 9, 0);
if (!active.dispatchEvent(event)) return document.activeElement;

var elms = [].slice.call(document.querySelectorAll('a,area,button,input,object,select,optgroup,textarea,[tabindex]'))
  .filter(function (e) { return !e.disabled && !e.readOnly && e.tabIndex >= 0 && e.offsetWidth > 0 && e.offsetHeight > 0 })
  .sort(function (a, b) { return (a.tabIndex || 0x1fffffff) - (b.tabIndex || 0x1fffffff) });

active.blur();
emit('blur', active);

var n = elms.length + elms.indexOf(active);
for (var attempts = 10; attempts--; ) {
  var next = elms[(n += (backward ? - 1 : 1)) % elms.length];
  next.focus();
  if (document.activeElement === next) {
    emit('focus', next);
    return next;
  }
}

return null;

function emit(type, target) {
  var event = document.createEvent('Event');
  event.initEvent(type, true, true);
  return target.dispatchEvent(event);
}