From what I have heard, the following is a "self-calling function":
func(){}();
How is it different from the following?
func(){} func();
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1 Answer
I assume you meant what is the difference between (I):
function(){}();
and (II):
function func(){};
func();
or even (III):
var func = function(){};
func();
All three behave the same in regard to the results, however they have different naming and scoping consequences:
I: this will not make the function available under any name, it is run once and forgotten. You can not reference it in the future
II:
funcfunction is created and available in the whole enclosing function, even before it is defined (hoisting)III:
funcvariable is defined pointing to a function. It won't be accessible before being defined.
Note that in II and III the function is referencable via func name and can be called again multiple times. This is not possible with self-calling function in I.
answered Sep 22, 2011 at 13:30
Tomasz Nurkiewicz
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2 Comments
wOlVeRiNe
Agreed, but then under what scenarios are self-calling functions used? I mean is there any specific need for them to be used in some sort of particular scenario?
iono
I know this is old but for other readers: you can wrap all of your own javascript in one big self-calling function so that it runs, but you know that it won't add a variable name to the global namespace - then, no other plugins like jQuery or anything else could accidentally use the same name as yours and clash.