SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<ul id="listOne">
 <li><a>Text 1</a></li>
 <li><a>Text 2</a></li>
 <li><a>Text 3</a></li>
 <li><a>Text 4</a></li>
</ul>

JavaScript

$("a").click(function(event){
  var pCount = $(this).closest('li').prevAll().length,
      nCount = $(this).closest('li').nextAll().length;
  if(pCount > 0 && nCount > 0){ alert("Previous and Next"); }
  else if(nCount > 0){ alert("Next"); }
  else if(pCount > 0){ alert("Previous"); } 
});