calling a optional parameter function

[(-: Dan :-)]

hi everybody

suppose I have a function in a DLL

function F1(var1, var2, var3)

where var2 and var3 are optional parameter with default value (for
exsample "-1")

I create a new instance of my class and then I call F1.
In VBS I can call function in 4 ways:
1. F1(1)
2. F1(1,2)
3. F1(1,2,3)
4. F1(1, ,3)

but in js the #4 generate error.

Can I call 4th way?

tnx Daniele

[rf]

Re: calling a optional parameter function


"(-: Dan :-)" <nntlodo@tiscal inet.it> wrote in message
news:3F86A2A0.D C175F1C@tiscali net.it...[color=blue]
> hi everybody
>
> suppose I have a function in a DLL
>
> function F1(var1, var2, var3)
>
> where var2 and var3 are optional parameter with default value (for
> exsample "-1")
>
> I create a new instance of my class and then I call F1.
> In VBS I can call function in 4 ways:
> 1. F1(1)
> 2. F1(1,2)
> 3. F1(1,2,3)
> 4. F1(1, ,3)
>
> but in js the #4 generate error.
>
> Can I call 4th way?[/color]

No.

Optional means from here on. You can not omit a parameter.

Cheers
Richard.

[Lasse Reichstein Nielsen]

Re: calling a optional parameter function

"(-: Dan :-)" <nntlodo@tiscal inet.it> writes:
[color=blue]
> 4. F1(1, ,3)[/color]
[color=blue]
> Can I call 4th way?[/color]

Try
F1(1,undefined, 3)

In Javascript, you can only omit arguments from a point. The effect
is that the parameter gets the value "undefined" , just as if you had
passed it as a value.

/L
--
Lasse Reichstein Nielsen - lrn@hotpop.com
Art D'HTML: <URL:http://www.infimum.dk/HTML/randomArtSplit. html>
'Faith without judgement merely degrades the spirit divine.'

[Lee]

Re: calling a optional parameter function

Lasse Reichstein Nielsen said:[color=blue]
>
>"(-: Dan :-)" <nntlodo@tiscal inet.it> writes:
>[color=green]
>> 4. F1(1, ,3)[/color]
>[color=green]
>> Can I call 4th way?[/color]
>
>Try
> F1(1,undefined, 3)[/color]

It would seem to be cleaner to supply the default value
as found in the documentation for that function:

F1(1,-1,3);

[Dr John Stockton]

Re: calling a optional parameter function

JRS: In article <bm6iuf01l1p@dr n.newsguy.com>, seen in
news:comp.lang. javascript, Lee <REM0VElbspamtr ap@cox.net> posted at Fri,
10 Oct 2003 08:23:59 :-[color=blue]
>Lasse Reichstein Nielsen said:[color=green]
>>"(-: Dan :-)" <nntlodo@tiscal inet.it> writes:
>>[color=darkred]
>>> 4. F1(1, ,3)[/color]
>>[color=darkred]
>>> Can I call 4th way?[/color]
>>
>>Try
>> F1(1,undefined, 3)[/color]
>
>It would seem to be cleaner to supply the default value
>as found in the documentation for that function:
>
> F1(1,-1,3);[/color]

Since F1 may be variable, perhaps supplied as a function parameter, the
actual value used for an undefined parameter may vary. Moreover, I have
a case where undefined actually means leaving out a bit of processing.
Zero would have the same effect, but waste time.

If an undefined value is needed, then define one. I believe that var U
does this in a satisfactory manner, though a longer name might be
preferred.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://jibbering.com/faq/> Jim Ley's FAQ for news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> JS maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/JS/&c., FAQ topics, links.

[(-: Dan :-)]

Re: calling a optional parameter function

>[color=blue]
>
> Since F1 may be variable, perhaps supplied as a function parameter, the
> actual value used for an undefined parameter may vary. Moreover, I have
> a case where undefined actually means leaving out a bit of processing.
> Zero would have the same effect, but waste time.
>
> If an undefined value is needed, then define one. I believe that var U
> does this in a satisfactory manner, though a longer name might be
> preferred.
>[/color]

I can't traslate correctly...... ... :-((

[Lasse Reichstein Nielsen]

Re: calling a optional parameter function

Lee <REM0VElbspamtr ap@cox.net> writes:
[color=blue]
> It would seem to be cleaner to supply the default value
> as found in the documentation for that function:
>
> F1(1,-1,3);[/color]

If you know the default value, and if there is one.

The default value for any omitted argument in Javascript *is*
undefined. However, you can only omit at the end of the argument list,
not in the middle.

A function can distinguish between
F1(1)
and
F1(1,undefined)
only by looking at arguments.lengt h, or by checking
'1' in arguments
(although it seems to be bugged in Opera)

/L
--
Lasse Reichstein Nielsen - lrn@hotpop.com
Art D'HTML: <URL:http://www.infimum.dk/HTML/randomArtSplit. html>
'Faith without judgement merely degrades the spirit divine.'

[Lasse Reichstein Nielsen]

Re: calling a optional parameter function

Dr John Stockton <spam@merlyn.de mon.co.uk> writes:
[color=blue]
> If an undefined value is needed, then define one. I believe that var U
> does this in a satisfactory manner, though a longer name might be
> preferred.[/color]

In ECMAScript, "undefined" is a global variable holding the undefined
value.
If you target non-ECMAScript browsers, you can ensure that it is defined
with a sigle, otherwise harmless, line:
window.undefine d = window.undefine d;
It has the advantage of working in any scope. If you know you are at
the root scope, you can just use
var undefined;

/L
--
Lasse Reichstein Nielsen - lrn@hotpop.com
Art D'HTML: <URL:http://www.infimum.dk/HTML/randomArtSplit. html>
'Faith without judgement merely degrades the spirit divine.'