Are these way to define function in javascript equal?

Question

I was wondering if the following way of writing function in javascript are equal.

To me it seems they produce the same result, but in what they can be different?

First way:

(function(){
    alert('ciao')
})();

Second way:

new function bar(){alert('ciao')};

Clear duplicate. http://stackoverflow.com/questions/1140089/how-does-an-anonymous-function-in-javascript-work (Could of milked this question :P ) — Layke, Sep 18 '11 at 20:49
Tongue in cheek answer: The difference is that the second is bad form and the first is generally acceptable. — beatgammit, Sep 18 '11 at 20:56

score 3 · Accepted Answer · answered Sep 18 '11 at 21:01

The second one returns a new instance of the function, as if it was a constructor.

So, these are equivelent:

Traditional method:

function bar() {
    this.x = 5;
};
var x = new bar();

Lazy one-liner.

var x = new function bar() { this.x = 5; };

The only difference is that you cannot reuse bar later.

If you don't believe me, try console.log(x.y); on both examples.

Your first example is an anonymous function which is not instantiated, it is just called.

Oscar Del Ben · Answer 2 · 2011-09-18T21:02:24.037

2

The first one executes the function and returns the result of it. The second one executes the function and returns an object.

EDIT: example:

enter image description here

edited Sep 18 '11 at 21:02

answered Sep 18 '11 at 20:54

Oscar Del Ben

2 Answers2