[jQuery] why coding like this:(function(){})();

(function(){})(); does it conform to the grammar?

[jQuery] what's the good things coding like this:(function(){})();

(function(){})(); what's the first () means? is this a standard grammar?and why coding like this?

[jQuery] About jquery append and automatic deleting

when you append by using an existing content, jquery will delete the orignal: $(new).append($('#ori')); then the orignal $('#ori') in the document will be deleted, is this by design?