Node.js JavaScript syntax

Question

I see a piece of JavaScript code in my Node.js application.

( function() { console.log("gg") } )(this)

I would like to know why use => ( function(){} )(this) this type of structure, and how does this compile.

I am understanding why we have this two brackets ()(), and why this code would work.

Ok, the interesting thing is though, why `(this)` is passed?!? — loveNoHate, Mar 07 '14 at 18:35

score 22 · Accepted Answer · edited May 23 '17 at 12:02

22

This is a self invoking anonymous function. This pattern is useful when you want to hide variables from the global namespace.

(function(){
    var foo = "foo";
})();

console.log(window.foo); // undefined

edited May 23 '17 at 12:02

Community

answered Mar 07 '14 at 18:30

webpapaya

1

How about (function(){})(this); Does "this" invoke this function? How about (function(global, requirejs, require){})(this, requirejs, require) ? – Terry Chen Mar 11 '14 at 19:20
1

these are just additional parameters which you can pass to the given function I'll fix this in my answer – webpapaya Mar 11 '14 at 20:02
i think this explains everything you need to know [link](http://stackoverflow.com/questions/5020479/what-advantages-does-using-functionwindow-document-undefined-windo) – webpapaya Mar 11 '14 at 20:12

1 Answers1