silverstripe-framework/javascript/src/SelectionGroup.js

import $ from './jQuery';

$(document).ready(function() {
	$('ul.SelectionGroup input.selector').live('click', function() {
		var li = $(this).closest('li');
		li.addClass('selected');

		var prev = li.prevAll('li.selected');
		if(prev.length) prev.removeClass('selected');
		var next = li.nextAll('li.selected');
		if(next.length) next.removeClass('selected');

		$(this).focus();
	});
});