Subj : Re: Strange ".constructor" behaviour -- I don't understand something,
To   : netscape.public.mozilla.jseng
From : Martin Honnen
Date : Tue Oct 04 2005 04:10 pm



Lev Serebryakov wrote:


> function Class() {}
> var c = Class();
> print(c.constructor);
> 
>  Yes, it outputs "function Class() {}". It is Ok. It is exactly what I
> expect.

The above snippet will give you an error alike 'c has no properties'.
Maybe you want
   var c = new Class();
as the second line?

>  Add some methods to this class:
> 
> function Class() {}
> Class.prototype = { method: function() {} };

You are not adding some methods you are creating a new prototype object 
that way.
If you want to add a method then do
   Class.protoype.methodName = function () {};

If you then do

function Class() {}
Class.prototype.methodName = function () {};
var c = new Class();

then c.constructor and c.methodName should be what you want.


Nevertheless the constructor property can be misleading if you build 
prototype based inheritance hierarchies but that is a known issue, try

function Class () {}
Class.prototype.methodName = function () {};

function SubClass () {}
SubClass.prototype = new Class();
SubClass.prototype.methodName1 = function () {};

var object = new SubClass();
print(object.constructor)

and you will get Class. It is what the ECMAScript specification wants 
however so you will often see code that manually corrects the 
constructor property as needed.

-- 

	Martin Honnen
	http://JavaScript.FAQTs.com/

.