JavaScript typeof checking a Request value

[Robert Mark Bram]

Hi All!

I have the following code in an asp page whose language tag is:
<%@LANGUAGE="JAVASCRIPT" CODEPAGE="65001"%>

// Find request variables.
var edition = Request.Form ("edition");
var language = Request.Form ("language");
Response.Write("Edition is type &quot;" + (typeof edition) + "&quot; and
value &quot;" + edition + "&quot;<br>");
Response.Write("Language is type &quot;" + (typeof language) + "&quot;
and value &quot;" + language + "&quot;<br>");

if (edition == "undefined" ||
(typeof edition) == "undefined")
{
Response.Write("Choose Page<br>");
Server.Execute ("choosePage.asp");
} // end if
else
{
Response.Write("View Page<br>");
Server.Execute ("viewPage.asp");
} // end else

The problem is this is what I see:

Edition is type "object" and value "undefined"
Language is type "object" and value "undefined"
View Page


There is nothing in choosePage.asp or viewPage.asp yet, but I am unable to
figure out why the else is triggering and not the if - my print out of the
edition var shows it has a value of "undefined"...

Any help would be most appreciated!

Rob
:)

[Lasse Reichstein Nielsen]

"Robert Mark Bram" <relaxedrob@removethis.optushome.com.au> writes:

> Response.Write("Edition is type &quot;" + (typeof edition) + "&quot; and
> value &quot;" + edition + "&quot;<br>");

....

> if (edition == "undefined" ||
> (typeof edition) == "undefined")

....

> Edition is type "object" and value "undefined"

So, edition is an *object*, and when it is converted to a string, it
becomes the string "undefined". I.e., edition.toString() == "undefined".

You then test whether edition=="undefined" . It isn't, since it is an
object, not a string, and objects are only equal to themselves.

Likewise, (typeof edition)=="undefined" fails since (typeof
edition)=="object".

> but I am unable to figure out why the else is triggering and not the
> if - my print out of the edition var shows it has a value of
> "undefined"...

No, its value is an object, which is neither the value "undefined" or
the string "undefined". That object has a method called toString that
returns the string "undefined".

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

[The Mighty Chaffinch]

> I have the following code in an asp page whose language tag is:

> <%@LANGUAGE="JAVASCRIPT" CODEPAGE="65001"%>
>
> // Find request variables.
> var edition = Request.Form ("edition");
> var language = Request.Form ("language");

I think you probably want the String value stored in the Request.Form.Item
object, not the object itself.
Try
var edition = String (Request.Form ("edition")),
language = String (Request.Form ("language"));

The variables should now contain either the string value from the form
field, or the string "undefined".

I hope this helps. I don't often see server-side JScript questions here,
most people seem to think that if it's ASP then it must be VBS.

MightyC

PS. I hope your user never types in "undefined" as a value!

> Response.Write("Edition is type &quot;" + (typeof edition) + "&quot;

and

>...(snipped)

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[Robert Mark Bram]

Hi MightyC! :)

Thanks for the response!

> var edition = String (Request.Form ("edition")),
> language = String (Request.Form ("language"));

OK, well this gets out the values as Strings..

> I hope this helps. I don't often see server-side JScript questions here,
> most people seem to think that if it's ASP then it must be VBS.

I spent a lot of time learning Javascript - I want to keep using it!

> PS. I hope your user never types in "undefined" as a value!

How on earth am I going to get around this?

Why isn't this a problem with VBScript?

Rob
:)

[The Mighty Chaffinch]

> Thanks for the response!

You're welcome!

> > var edition = String (Request.Form ("edition")),
> > language = String (Request.Form ("language"));

>
> OK, well this gets out the values as Strings..

It will invoke the toString method for the object, which is what you want.

> > I hope this helps. I don't often see server-side JScript questions here,
> > most people seem to think that if it's ASP then it must be VBS.

>
> I spent a lot of time learning Javascript - I want to keep using it!

Amen to that!

> > PS. I hope your user never types in "undefined" as a value!

>
> How on earth am I going to get around this?

I use code like this:

var action = (typeof (Request.Form.Item ("action")) == "undefined")
? null
: String (Request.Form.Item ("action"));

It's a bit clumsy but I've never come up with anything better. Now you can
test for empty field (ie. == null) and use a default value or send an error
or whatever.

> Why isn't this a problem with VBScript?

Dunno. Never used VBScript :)

Happy JavaScript
MightyC



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[Robert Mark Bram]

Hi again!

> I use code like this:
>
> var action = (typeof (Request.Form.Item ("action")) == "undefined")
> ? null
> : String (Request.Form.Item ("action"));

Except that I am finding this:
typeof (Request ("notThere"))
or
typeof (Request.Form.Item ("notThere"))
returns
"object"

and not "undefined"

Rob
:)

[Steve van Dongen]

On Sun, 19 Oct 2003 12:28:15 +1000, "Robert Mark Bram"
<relaxedrob@removethis.optushome.com.au> wrote:

>Hi again!
>

>> I use code like this:
>>
>> var action = (typeof (Request.Form.Item ("action")) == "undefined")
>> ? null
>> : String (Request.Form.Item ("action"));

>
>Except that I am finding this:
> typeof (Request ("notThere"))
>or
> typeof (Request.Form.Item ("notThere"))
>returns
> "object"
>
>and not "undefined"

Yes, that's correct, it's a collection. As I said in your other
thread I usually just convert it to a string immediately and handle
undefined later. However, this is the "proper" way to do it:

var foo = Request.Form("foo").Count == 0
? null
: Request.Form("foo").item()

item() will return a string of all the foo arguments concatenated
together and delimited by commas, for example, if you have
?foo=123&foo=456 then .item() will return "123, 456". If you could
potentially have multiple instances of the same argument and the value
may contain a comma then you should loop through the collection using
..item(i), which returns the i-th foo argument, to be sure you handle
the values correctly.

Regards,
Steve

[Steve van Dongen]

On Sat, 18 Oct 2003 22:04:04 +0000 (UTC), "The Mighty Chaffinch"
<mightychaffinch@hotmail.com> wrote:

>> > var edition = String (Request.Form ("edition")),
>> > language = String (Request.Form ("language"));

>>
>> OK, well this gets out the values as Strings..

>
>It will invoke the toString method for the object, which is what you want.

These are not JScript objects; they don't have a toString() method.
String(edition) calls the default method for the object which, in this
case, happens to be item().

Regards,
Steve

[Robert Mark Bram]

Howdy Steve - thank you very much for your response!

(from your other reply)

> These are not JScript objects; they don't have a toString() method.
> String(edition) calls the default method for the object which, in this
> case, happens to be item().

*the fog begins to lift* .. :)

> Yes, that's correct, it's a collection.

....

> var foo = Request.Form("foo").Count == 0
> ? null
> : Request.Form("foo").item()

Now that I see it is a collection, this is exactly what I wanted!

Rob
:)