In dataToDom and findValueCallback methods innerHTML properity is used to fill list elements with results. While this is tolerable for

HTML4 formatted pages it breaks plugin in XHTML environment.

Consider server side script returning results that contain ampersand ("A&M" for example). If you return it without modification it'll create the following invalid DOM:

<ul>
<li>A&M</li>
</ul>

(that happens because innerHTML does not properly escape passed value and does not convert & to entity &).

If you return "A&M" from server side script it'll create valid DOM, but will put invalid value in select element ("A&M" instead of "A&M"), so this is not a good solution.

The right thing to do to use document.createTextNode() method instead of innerHTML:

var li = document.createElement("li");
var tn = document.createTextNode(row[0]);
li.appendChild(tn);