gistfile1.js

$("#search").keydown(function(e) {
  var $resultsUl = $("#suggested-result");
  var $currentSelection = $resultsUl.find("li.highlighted:visible");
  
  if ($currentSelection.length == 0) return;

  if (e.keyCode == 40) { // keyCode 40 == down
    var $next = $currentSelection.next();
    
    if ($next.length > 0) {
      $currentSelection.removeClass("highlighted");
      $next.addClass("highlighted").focus();
      
      if (! $next.is(":visible")) {
        $resultsUl.scrollTop(
          $next.offset().top - $resultsUl.offset().top + $next.height()
        );
      }
    }
  }
  
  if (e.keyCode == 38) { // KeyCode 38 == up
    var $prev = $currentSelection.prev();
    
    if ($prev.length > 0) {
      $prev.addClass("highlighted").focus();
      $currentSelection.removeClass("highlighted");
      
      if (! $prev.is(":visible")) {
        $resultsUl.scrollTop(
          $prev.offset().top - $resultsUl.offset().top + $prev.height()
        );
      }
    }
  }
  
  if (e.keyCode == 13) { // KeyCode 13 == enter
    window.location = $currentSelection.find("a").attr("href");
    e.preventDefault();
  }
});