design patterns - How do you explain this structure in JavaScript?

Question

(function() 
 {
     //codehere
 }
)();

What is special about this kind of syntax? What does ()(); imply?

Answer 1

The creates an anonymous function, closure and all, and the final () tells it to execute itself.

It is basically the same as:

function name (){...}
name();

So basically there is nothing special about this code, it just a 'shortcut' to creating a method and invoking it without having to name it.

This also implies that the function is a one off, or an internal function on an object, and is most useful when you need to the features of a closure.