Question

$("span:last-child").hide("fast", function () {
        $(this).prev().hide("fast", arguments.callee); 
    });

I can’t understand this point in the code:

1. ("span:last-child"): what is this?

2. arguments.callee: what is this?

Answer 1

$ is the main jQuery function.

$("span:last-child") searches for any <span> tags that are the last child of their parent.

Finds:

<div><span>some data </span> something else <span>testing</span></div>

It would find the span that includes testing but not the some data.

It then hides those spans it found. The second argument to hide is a callback after the animation. That callback goes to the “previous” child (the ‘something else’ text node), hiding it and passing the “called function” (arguments.callee) as the callback. Which makes this a “recursive” function.

This would hide the entire contents of all blocks that have a <span> as their last child.