"Tabindex loop" example

HTML

<div id="focusguard-1"></div><!--  -->
<input id="firstInput focusguard-1" type="text" autofocus tabindex="1" />
<input type="text" tabindex="2" />
<input type="text" tabindex="3" />
<input type="text" tabindex="4" />
<input type="text" tabindex="5" />
<input id="lastInput focusguard-2" type="text" tabindex="6" />
<div id="focusguard-2" tabindex="7"></div>

JavaScript

$('#focusguard-2').on('focus', function() {
  $('#firstInput').focus();
});

$('#focusguard-1').on('focus', function() {
  $('#lastInput').focus();
});