How to build a reference to a global variable

[johkar]

This is a bit tricky to describe, but here goes. Any help
appreciated. John

I declare multiple variables halfway down the page. The number
between "mech" and "Num" is generated dynamically in the XSL. Later
on I need to reference that variable in a function, but I need to
build the variable name in script. How do I convert it from a string
reference to a ref to the global variable?


function changePreferenc e(pos,mt){
//mt does not reference mech2Num, I need it to.
}
changePreferenc e(2,'my' + pos + 'Num');


var mech1Num=1|2|3| 4|5|6;
var mech2Num=1|2|3| 4|5|6;
var mech3Num=1|2|3| 4|5|6;

[Randy Webb]

Re: How to build a reference to a global variable

johkar wrote:
[color=blue]
> This is a bit tricky to describe, but here goes. Any help
> appreciated. John
>
> I declare multiple variables halfway down the page. The number
> between "mech" and "Num" is generated dynamically in the XSL. Later
> on I need to reference that variable in a function, but I need to
> build the variable name in script. How do I convert it from a string
> reference to a ref to the global variable?
>
>
> function changePreferenc e(pos,mt){
> //mt does not reference mech2Num, I need it to.
> }
> changePreferenc e(2,'my' + pos + 'Num');
>
>
> var mech1Num=1|2|3| 4|5|6;
> var mech2Num=1|2|3| 4|5|6;
> var mech3Num=1|2|3| 4|5|6;[/color]

So you want "mech" + # + "Num" as a dynamic variable name? Simple:

window["mech" + # + "Num"]

Will give you a reference to it.

--
Randy

[johkar]

Re: How to build a reference to a global variable

Randy Webb <HikksNotAtHome @aol.com> wrote in message news:<7p-dnd0NXLEO7BvcRV n-sw@comcast.com> ...[color=blue]
> johkar wrote:
>[color=green]
> > This is a bit tricky to describe, but here goes. Any help
> > appreciated. John
> >
> > I declare multiple variables halfway down the page. The number
> > between "mech" and "Num" is generated dynamically in the XSL. Later
> > on I need to reference that variable in a function, but I need to
> > build the variable name in script. How do I convert it from a string
> > reference to a ref to the global variable?
> >
> >
> > function changePreferenc e(pos,mt){
> > //mt does not reference mech2Num, I need it to.
> > }
> > changePreferenc e(2,'my' + pos + 'Num');
> >
> >
> > var mech1Num=1|2|3| 4|5|6;
> > var mech2Num=1|2|3| 4|5|6;
> > var mech3Num=1|2|3| 4|5|6;[/color]
>
> So you want "mech" + # + "Num" as a dynamic variable name? Simple:
>
> window["mech" + # + "Num"]
>
> Will give you a reference to it.[/color]

Thanks, I hadn't come across that method, I ended up using eval(). I
need to look up which is supported by more browsers.

John

[Michael Winter]

Re: How to build a reference to a global variable

On 2 Nov 2004 03:55:41 -0800, johkar <nosendjunk@msn .com> wrote:
[color=blue]
> Randy Webb <HikksNotAtHome @aol.com> wrote in message
> news:<7p-dnd0NXLEO7BvcRV n-sw@comcast.com> ...[/color]

[snip]
[color=blue][color=green]
>> window["mech" + # + "Num"]
>>
>> Will give you a reference to it.[/color]
>
> Thanks, I hadn't come across that method,[/color]

It's given a lot of detail in the FAQ notes
(<URL:http://www.jibbering.c om/faq/faq_notes/square_brackets .html>).
[color=blue]
> I ended up using eval().[/color]

Don't. The eval function is slower and tends to lead to errors and bad
practice. Most people start seeing it as some kind of magic-wielding,
catch-all function that will accomplish whatever the author wants. It
actually has a specific use that most people will *never* need.
[color=blue]
> I need to look up which is supported by more browsers.[/color]

Both just as well, but bracket notation is *much* preferred.

Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.

[Richard Cornford]

Re: How to build a reference to a global variable

Michael Winter wrote:[color=blue]
> johkar wrote:[/color]
<snip>[color=blue][color=green]
>> I need to look up which is supported by more browsers.[/color]
>
> Both just as well, but bracket notation is *much* preferred.[/color]

They are not quite equally supported. ECMA 327 ('ECMAScript Compact
Profile') allows implementations for small devices to have an - eval -
function that does no more than throw exceptions, and the AvantGo 3
browser (for PDAs, and getting on a bit now) did not implement - eval -
at all.

Richard.

[Michael Winter]

Re: How to build a reference to a global variable

On Tue, 2 Nov 2004 20:58:21 -0000, Richard Cornford
<Richard@litote s.demon.co.uk> wrote:
[color=blue]
> Michael Winter wrote:[/color]

[snip]
[color=blue][color=green]
>> Both [eval and bracket notation work] just as well, but bracket
>> notation is *much* preferred.[/color]
>
> They are not quite equally supported.[/color]

[snip]

I didn't know that, but then again, I've never read the Compact Profile,
nor have I ever used AvantGo.

Thanks for the correction, particularly as it serves to reaffirm the
latter part of the sentence.

Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.

[johkar]

Re: How to build a reference to a global variable

Thanks. Good info. John

[Dr John Stockton]

Re: How to build a reference to a global variable

JRS: In article <cm8sdf$ip5$1$8 30fa17d@news.de mon.co.uk>, dated Tue, 2
Nov 2004 20:58:21, seen in news:comp.lang. javascript, Richard Cornford
<Richard@litote s.demon.co.uk> posted :
[color=blue]
>ECMA 327 ('ECMAScript Compact
>Profile')[/color]

<FAQENTRY> ECMA 327

--
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