What (function(){})(); mean? [duplicate]

Question

Possible Duplicate:
What does this “(function(){});”, a function inside brackets, mean in javascript ?

(function(){
    ---this code at here ----
})();

What does (function(){})(); mean? Please explain it to me.

Answer 1

It makes an anonymous function and executes it. You use it to prevent variables from poluting the global scope.

(function(){
  var test = "Hello";
})();

alert(test); //test will be undefined here