buildFragment() uses jQuery.clean() to extract the JS code of <script> elements. If it uses the cached DOM Fragment, clean() isn't called. In this case, the 'scripts' array remains empty so that evalScript() isn't called any longer.

Test case:

<p><a href="" id="start">call html()</a></p>

<div id="output"></div>

<script>

$(function ($) {

$('#start').click(function (e) {

$('#output').html("<script> alert('should be executed'); <\\/script>");

e.preventDefault();

});

});

</script>

This works as expected for the first and second click, but the third time the cache kicks in and the embedded script isn't executed.

This used to work in jQuery 1.3. I've encountered this bug in an Ajax environment using .load(). If the Ajax response is the same three times in a row, the embedded scripts weren't executed.