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Re: Declarations (esp. of Globals)

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Mike Duffy wrote:

> Gene Wirchenko <genew@ocis.net> wrote […]:
>>      I am a stickler for declarations and prefer to declare
>> everything.  As applied to JavaScript, what say you?  And why?
> 
> I agree 100%. In the case of Javascript, even more so.

There is no "Javascript" [1].

However, in ECMAScript implementations like JavaScript, JScript, etc., 
variable declarations are important:

If you do not declare an identifier a variable, and assign to it, one of 
three things can happen: nothing (no effect at all, because an existing 
property was read-only), an exception is thrown (because an existing 
property could not be overwritten or created), or a property of the global 
object is being created or overwritten (sometimes called an "implied 
global").

With a variable declaration, the scope of a standalone identifier is clear.

That is why in ECMAScript Edition 5.x's Strict Mode¹, such an assignment, if 
the identifier cannot be resolved, always throws a ReferenceError exception.  
You can attempt to trigger Strict Mode with

  "use strict";

on top of the code or function body.

See also: <https://developer.mozilla.org/en/JavaScript/Strict_mode>


PointedEars
___________
¹ not to be confused with layout engines' Standards (Compliance) Mode

[1] <http://PointedEars.de/es-matrix>
-- 
Prototype.js was written by people who don't know javascript for people
who don't know javascript. People who don't know javascript are not
the best source of advice on designing systems that use javascript.
  -- Richard Cornford, cljs, <f806at$ail$1$8300dec7@news.demon.co.uk

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Thread

Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-28 18:25 -0800
  Re: Declarations (esp. of Globals) Mike Duffy <Use_guestbook_page@website.in.sig> - 2011-11-29 03:39 +0000
    Re: Declarations (esp. of Globals) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-11-29 13:28 +0100
      Re: Declarations (esp. of Globals) John G Harris <john@nospam.demon.co.uk> - 2011-11-29 15:39 +0000
        Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-29 12:17 -0800
          Re: Declarations (esp. of Globals) Mike Duffy <Use_guestbook_page@website.in.sig> - 2011-11-29 20:43 +0000
            Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-29 13:48 -0800
              Re: Declarations (esp. of Globals) Mike Duffy <Use_guestbook_page@website.in.sig> - 2011-11-29 22:11 +0000
                Re: Declarations (esp. of Globals) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-11-29 23:52 +0100
                Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-29 15:11 -0800
                Re: Declarations (esp. of Globals) Scott Sauyet <scott.sauyet@gmail.com> - 2011-11-30 04:31 -0800
                Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-30 14:18 -0800
                Re: Declarations (esp. of Globals) Scott Sauyet <scott.sauyet@gmail.com> - 2011-12-01 06:31 -0800
                Re: Declarations (esp. of Globals) "Tom de Neef" <tdeneef@qolor.nl> - 2011-12-01 11:34 +0100
                Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-12-01 11:57 -0800
          Re: Declarations (esp. of Globals) Scott Sauyet <scott.sauyet@gmail.com> - 2011-11-29 13:36 -0800
            Re: Declarations (esp. of Globals) Gene Wirchenko <genew@ocis.net> - 2011-11-29 15:13 -0800
            Re: Declarations (esp. of Globals) John G Harris <john@nospam.demon.co.uk> - 2011-11-30 17:03 +0000
        Re: Declarations (esp. of Globals) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-11-29 23:42 +0100

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