How to check if an element is hidden in jQuery?

Often when checking if something is visible or not, jQuery chaining makes this simple.

So if you have a selector and you need to play out some activity on it only if is visible or hidden, you can utilize filter(":visible") or filter(":hidden") trailed by chaining it with the action you want to make.

if statement example:

if ($('#btnUpdate').is(":visible"))
{
     $('#btnUpdate').animate({ width: "toggle" });   // Hide button
}

You can do it all in one line:

$('#btnUpdate').filter(":visible").animate({ width: "toggle" });