Knowing if an element is in the DOM using jQuery

If you ever need to know if the element you have a reference to is really in your page (or if it is an old reference to an element you've already replaced), you can use the $.contains(container, contained) method.

I was just working on an AJAX paginated list of elements and I kept references to my table in vars to avoid re-querying it each time. But this reference where still 'correct' (ie. not null) even after having replaced the element with a new one (using .replaceWith() and even .empty() and .remove())

I added a check to see if the element was really in the DOM before using it, and if not requerying it and re-saving it in var