javascript anonymous function [duplicate]

Answer 1

Your code sample

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

can be rewritten as

anonymous = function () { ... };
(anonymous)();

or, avoiding the redundant first brace pair, as

anonymous = function () { ... };
anonymous();

at the cost of introducing a name into the (here global) name space.

As pointed out by pst earlier, this construction is used to create a new scope. It is most useful in combination with closures, for example to implement the ubiquitous counter:

 var counter = function (initval) {
   var c = initval || 0;
   return function () {
    var r = c;
    c += 1;
    return r;
   };
} (5);

counter () ; // 5
counter () ; // 6
counter () ; // 7