Formatting strings

[Nige]

I'm a complete novice to JS. I want to insert the date and time into a
document in the format:

WB-MMDDHHmm

Where:

WB- is a fixed string prefix (the whole string is a reference number)
MM is the month 01 to 12, with a leading 0 if required
DD is the day 01 to 31, with a leading 0 if required
HH is the hour 00 to 23, with a leading 0 if required
mm is the minute 00 to 59, with a leading 0 if required
I've got this far:
<script language="JavaS cript">

function ShowDateTime()
{
var today = new Date();
var mo=today.getMon th()+1;
var da=today.getDat e();
var ho=today.getHou rs();
var mi=today.getMin utes();

# parse here #

document.write( "WB-"+mo+da+ho+ mi);
}

</script>
The problem is the bit to parse the strings, I've tried

if (mo.length < 2) mo="0"+mo; ... etc

but it doesn't work.

Help!
--
Nige

Please replace YYYY with the current year
ille quis mortem cum maximus ludos, vincat

[Thomas 'PointedEars' Lahn]

Nige wrote:

function ShowDateTime()
{
var today = new Date();
var mo=today.getMon th()+1;
var da=today.getDat e();
var ho=today.getHou rs();
var mi=today.getMin utes();

# parse here #

document.write( "WB-"+mo+da+ho+ mi);
}
[...]

The problem is the bit to parse the strings, I've tried

if (mo.length < 2) mo="0"+mo; ... etc

but it doesn't work.

The Date.get...(... ) methods return values of type `number'. When you assign
them to a variable and use the lookup operator `.' with that variable, the
value stored in that variable is converted to a Number object.
Unfortunately, those objects do not have a `length' property, so the value
is `undefined'. But `undefined < 2' equals `false' (as you can and should
test with alert(...) or document.write( ...)) so the second assignment to
`mo' aso. is not executed.

I see two possible approaches to solve the problem:

A) Convert the number into a string. String objects have a
length property you can compare with:

if (String(mo).len gth < 2)
...

B) What you need is only the leading zero for a two-digit number.
So concatenate it only when it is needed, as the number is less
than 10:

if (mo < 10)
...

I use and recommend to use B) since it is faster and allocates less memory.
HTH

PointedEars

[Nige]

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:

The Date.get...(... ) methods return values of type `number'.

Of course, thank you.

I've since realized that the problem is more complex than I thought. The
plan was to generate a reference number consisting of the date and time
when a user submits a form.

The reference number is created by the CGI script that processes the
form, but (of course) if the user's clock is not the same as the server
then the numbers are different. D'OH!

Is there a way to generate a string referencing the current date and
time (as MMDDHHmm) when a user presses the Submit button, send this
string with the other form data, then display this string on the page
that is displayed next?

--
Nige

Please replace YYYY with the current year
ille quis mortem cum maximus ludos, vincat

[Thomas 'PointedEars' Lahn]

Nige wrote:

I've since realized that the problem is more complex than I thought. The
plan was to generate a reference number consisting of the date and time
when a user submits a form.

The reference number is created by the CGI script that processes the
form, but (of course) if the user's clock is not the same as the server
then the numbers are different. D'OH!

Null problemo. You should never use client-side data when server-side data
is more reliable. Did you think of timezones and stuff like that? Use the
server time for generating the reference number which also frees you from
dependence of client-side JavaScript support and unreliable techniques (like
changing the value of an `input' element on submit which could, but should
not be done here.)
PointedEars

P.S.
Please don't change the Subject unless there is really a change of subject.

[Nige]

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:

Use the server time for generating the reference number

I don't know how to make the CGI script send a value to the next page.

--
Nige

Please replace YYYY with the current year
ille quis mortem cum maximus ludos, vincat

[Nige]

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:

You should never use client-side data when server-side data
is more reliable.

Time zones don't enter into it, all users are in the UK. All I really
need is a reference number that gives the date and approx time, it
doesn't even have to be unique, but the user must be shown the same
number that I get sent by the CGI.

As I said in my other post (which I sent without giving full details,
sorry), I can't send the CGI data to the next page. So the simple option
(assuming it is simple) is the generate a string on the form page, send
it with the CGI data, and display it on the following page.

Can it be done?
--
Nige

Please replace YYYY with the current year
ille quis mortem cum maximus ludos, vincat

[Thomas 'PointedEars' Lahn]

Nige wrote:

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:

Use the server time for generating the reference number

I don't know how to make the CGI script send a value to the next page.

This is off-topic here (since it has nothing to do with JavaScript)
but what kind of CGI script are you talking about?
PointedEars

P.S.
Don't expect people to manipulate the `To' when they send you e-mail.

[HikksNotAtHome]

In article <bo************ *@ID-107532.news.uni-berlin.de>, Thomas 'PointedEars'
Lahn <Po*********@we b.de> writes:

Nige wrote:

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:

Use the server time for generating the reference number
I don't know how to make the CGI script send a value to the next page.

This is off-topic here (since it has nothing to do with JavaScript)
but what kind of CGI script are you talking about?

Server Side Javascript potentially running as a CGI is off-topic in a
Javascript newsgroup?
PointedEars

P.S.
Don't expect people to manipulate the `To' when they send you e-mail.

Dont try to email people from a group and its a non-issue. Post to news, get
answered in news, and theres no problem.
--
Randy

[Thomas 'PointedEars' Lahn]

HikksNotAtHome wrote:

In article <bo************ *@ID-107532.news.uni-berlin.de>, Thomas 'PointedEars'
Lahn <Po*********@we b.de> writes:

....

Nige wrote:

In comp.lang.javas cript, Thomas 'PointedEars' Lahn wrote:
Use the server time for generating the reference number

I don't know how to make the CGI script send a value to the next page.

This is off-topic here (since it has nothing to do with JavaScript)
but what kind of CGI script are you talking about?

Server Side Javascript potentially running as a CGI is off-topic in a
Javascript newsgroup?

Of course not, but nothing was said about server-side JavaScript and I
assumed that the OP did not wrote about server-side JavaScript because
he distiguished CGI from that (which is incorrect, though.)

P.S.
Don't expect people to manipulate the `To' when they send you e-mail.

Dont try to email people from a group and its a non-issue. Post to news, get
answered in news, and theres no problem.

Usenet is public newsgroups *and* private (e-)mail (PM), at least because
it is obvious that some things do not belong into newsgroups but are better
to be written via e-mail than not written at all (as the Netiquette
recommends.) I'm sorry for you that you are not aware of this, but that
is your problem, not mine.
EOD

PointedEars

[HikksNotAtHome]

In article <bo************ *@ID-107532.news.uni-berlin.de>, Thomas 'PointedEars'
Lahn <Po*********@we b.de> writes:

Dont try to email people from a group and its a non-issue. Post to news,

get

answered in news, and theres no problem.

Usenet is public newsgroups *and* private (e-)mail (PM), at least because
it is obvious that some things do not belong into newsgroups but are better
to be written via e-mail than not written at all (as the Netiquette
recommends.) I'm sorry for you that you are not aware of this, but that
is your problem, not mine.

I have no problem with it. I dont recieve the mails (If I do, they get
deleted), so I fail to see how Usenet is a "private" place. As I said, don't
try to email someone, no problems. Trying to get outside of the public Usenet
into private Email is crossing a boundary that I don't care to cross. It opens
up too many problems. If the "Netiquette " says its ok, I don't care, I don't do
it and I won't do it.
--
Randy