Re: Language Confusions

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From	"J.R." <groups_jr-1@yahoo.com.br>
Newsgroups	comp.lang.javascript
Subject	Re: Language Confusions
Date	Thu, 24 Nov 2011 00:07:46 -0200
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On 23/11/2011 23:38, Gene Wirchenko wrote:
> Dear JavaScripters:
>
>       I have been carefully studying JavaScript and have learned a lot
> more than I ever knew about it.  I have some questions about niggling
> points:
>
>    1) What is the difference between:
>            s="Hello";
>            s=new String("Hello");
>            s=String("Hello");
> The text I am studying says that the first two are the same.  Fine.
> The third behaves the same way AFAICS.  Could someone please
> illustrate the difference?
>

If you paste the following code snippet in a JavaScript console such as 
Firebug's (in Firefox), you will notice the difference:

   var s1 = "Hello",
       s2 = new String("Hello"),
       s3 = String("Hello");

   console.log(typeof s1); // "string"
   console.log(typeof s2); // "object"
   console.log(typeof s3); // "string"

So "the first two are the same" is wrong... Check the ECMAScript 
Language Specification to learn the why's.

>    2) I am unclear on exactly all what .prototype does.  For adding
> methods to an object type, fine.  In the text that I am studying,
> there is an example of a table object.  The author then shows how to
> add a method to an object type (without modifying the base code), and
> how it is done has me puzzled:
>            function table_colorWrite(doc)
>               body omitted
> followed by
>            table.prototype.colorWrite=table_colorWrite
> I am not clear on what .prototype does in this line.  I think I must
> be missing something about the JavaScript object model.

An explanation about prototype in JavaScript would require a lot of 
typing here... So I'd suggest a further reading at 
<http://javascript.crockford.com/prototypal.html>

-- 
Joao Rodrigues (J.R.)

Thread

Language Confusions Gene Wirchenko <genew@ocis.net> - 2011-11-23 17:38 -0800
  Re: Language Confusions "J.R." <groups_jr-1@yahoo.com.br> - 2011-11-24 00:07 -0200
  Re: Language Confusions Richard Cornford <Richard@litotes.demon.co.uk> - 2011-11-24 05:41 -0800
    Re: Language Confusions Gene Wirchenko <genew@ocis.net> - 2011-11-24 11:27 -0800

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