Difference between (function(){})(); and function(){}();

Question

This is something I haven't quite figured out yet, but I have been using function(){}() just because my VIM syntax highlight screws up if I add the parenthesis, although I've seen (function(){})() around many times, maybe its an IE thing?

edit:

var singleton = function() {
    // code
}();

var singleton = (function() {
    // code
})();

Answer 1

Is there a difference? Are you seeing a difference in execution at all? This is a super interesting question.

Answer 2

wild guess : there is no difference.

Answer 3

The extra set of parentheses makes it clearer that you are constructing a function and then calling it. It's a coding style thing, not a functionality thing.

Answer 4

function(){}();

doesn't work in most of browsers. You should use parenthesis around the function in order to execute it

(function(){})();

then browser will know that last parenthesis should be applied to all the expression

function(){}

UPD: If you don't use parenthesis, the brower could misunderstand you. If you just call the function and dismiss the result

function() {
    alert(1);
}();

then ff and ie will throw error

Answer 5

Peter Michaux discusses the difference in An Important Pair of Parens.