Another point of view
First, you can declare an anonymous function:
var foo = function(msg){
alert(msg);
}
Then you call it:
foo ('Few');
Because foo = function(msg){alert(msg);} so you can replace foo as:
function(msg){
alert(msg);
} ('Few');
But you should wrap your entire anonymous function inside pair of braces to avoid syntax error of declaring function when parsing. Then we have,
(function(msg){
alert(msg);
}) ('Few');
By this way, It's easy understand for me.