Consider this minimalistic standalone example using jQuery.ui slidetoggle:
<html>
<head>
<title>Toggle Test</title>
<link rel="stylesheet" href="//ajax.googleapis.com/ajax/libs/jqueryui/1.11.2/themes/smoothness/jquery-ui.css"/>
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//ajax.googleapis.com/ajax/libs/jqueryui/1.11.2/jquery-ui.min.js"></script>
<style type="text/css">
</style>
<script type="text/javascript">
$(document).ready(function () {
$('#fold').click(function () {
$('.inner').slideToggle(2000);
});
});
</script>
</head>
<body>
<div id="fold">+-</div>
<div class="inner">
TESTTESTTESTTESTTESTTESTTESTTEST<br/>
TESTTESTTESTTESTTESTTESTTESTTEST<br/>
TESTTESTTESTTESTTESTTESTTESTTEST<br/>
TESTTESTTESTTESTTESTTESTTESTTEST<br/>
</div>
</body>
</html>
Expected behavior: clicking on the #fold element collapses the .inner element with a 2-second animation (changing the height).
This works when I load the page in Firefox for the first time.
However, as soon as I open the Dom-Inspector in Firefox and select for example the .inner element the behavior changes:
A click will result in changing the element's display to none after 2 seconds (as before) but the animation is gone.
In chrome everything is alright.
Note1: I am using FF33.0 from the ubuntu reps. When trying to reproduce this with jsfiddle, make sure, that the content of the lower-right Iframe is actually displayed in the DOM-Inspector.
Note2: I am working on a JSON editor and came across this issue when trying to implement fold-marks. There the toggle-animation is always missing in Firefox. I hope the solution to this simple Problem yields a hint.