From the jquery-dev list:

does anybody have any experience/success with running jQuery inside a Mozilla Firefox sandbox, in which the global window object is a deep XPCNativeWrapper of the underlying DOM?

In this environment, 'expando' properties - e.g., properties not defined by W3C DOM may be added only to 'window' and 'document', but not to any other DOM element. For example, the following code:

document.expando = 'Hello'; document.body.expando = 'World'; alert(document.expando + ' ' + document.body.expando);

would alert 'Hello undefined'.

Is it possible to use jQuery if DOM elements do not support expando properties?

Attempting animate stuff like "padding-left" or "margin-left" doesn't work (it needs to be paddingLeft or marginLeft). That converion should happen automatically.

Seeing a major slowdown in .html() performance when performed on a large page.