How to modify this script to allow negative numbers??

**RobG** · Nov 28 '05, 01:55 AM

Re: How to modify this script to allow negative numbers??

tlyczko wrote:[color=blue]
> Hello Rob B posted this wonderful code in another thread,
>
> http://groups.google.com/group/comp....ad9d5e61be85f0
>
> I could not figure out how to reply to the thread per se using Google
> Groups and so please forgive me for cutting and pasting (I emailed him
> but he may not have time to check his email), and I am hoping someone
> might be able to tell me how I can change this script to allow negative
> numbers.[/color]

There's probably not much point in replying to a thread that is 12
months old.
[color=blue]
>
> My question is:
>
> How can I modify it to allow a minus sign to allow negative numbers??
>[/color]

Very probably, but the script itself is very much more complex than need
be. What are you trying to do? If you want to restrict user input to 5
digits, one decimal point and two more digits, then use a regular
expression, there are many here that can be modified for your purpose:

<URL: http://www.merlyn.demon.co.uk/js-valid.htm#VNP >

The one you want is:

/^[-]?\d{0,5}(\.\d{0 ,2})?$/

I loath scripts that modify what I am typing as I type it. It is much
better to show a message adjacent to the input box to remind the user
that the format is not what you want and allow them to modify it. Many
users will simply type the extra digits anyway and likely not notice
that you've removed them. And if they have JavaScript disabled, your
script will not do anything.

Don't use an alert (especially as this seems to be for an intranet where
the users are likely experienced data input operators), that is even
worse. An example is below.

<script type="text/javascript">
//<![CDATA[

function testNum(num, erId){
var er = document.getEle mentById(erId);
var re = /^[-]?\d{0,5}(\.\d{0 ,2})?$/;
if (num && !re.test(num) ) {
er.innerHTML = 'Invalid number, required format is [-]nnnnn.nn';
} else {
er.innerHTML = '';
}
}

//]]>
</script>
</head><body>
<form action="">
$ <input type="text" name="foo" value="" size="10" maxlength="9"
onkeyup="testNu m(this.value, 'msg');" />
<input type="reset" value="clear" />
</form>
<div id="msg"></div>
</body>

[color=blue]
> I want to use it in a purchase requisition form where sometimes
> negative numbers are necessary.[/color]

The above is not production ready, it just gives you a start and an
example of how to use a regular expression more efficiently.

[color=blue]
> Ideally I want to allow a negative number typed in, then when it goes
> to be printed I would want to reformat it (either with JS or CSS) so it
> has ( ) to show it is
> a negative/credit type of number for Accounts Payable to act
> accordingly.[/color]

Then use onblur to add the parenthesis. But you have limited the number
of characters in the input box, so how will you add the extra two
characters? If you modify the input's 'length' parameter, then the user
can go back, remove the brackets and add more numbers - so you have some
UI issues to deal with. Your original doesn't allow room for the minus
sign (unless you wanted 4 digits before the decimal).

Or do you write the value to somewhere else in the page?

[...]

--
Rob

**tlyczko** · Nov 28 '05, 11:05 AM

Re: How to modify this script to allow negative numbers??

Thank you for your help!!

I am RE-learning Javascript as I go. You were right, it was a
1-year-old thread, I gambled and hopefully we have something here
others can learn from.

Merlyn's Javascript pages are wonderful but I find them sometimes
rather abstract, because he uses a lot of includes to present things on
his site and sometimes the demos etc. require the include files, so it
can be a little difficult figuring out what to use.

Thank you for the specific link, though. I missed it completely when I
was reading his site before I found this script.

A few hours after posting, I also found a great website,
http://www.regexlib.com, which is a fantastic resource for regex
patterns.

I found one regex that although it is rather long, allows me to enter $
and enclosing parentheses (and even commas), which are necessary for
credits (to be subtracted) rather than debits (which will be added).
Purchase requisitions rarely have credits, usually everything is added
up.

The link for the regex is

http://www.regexlib.com/REDetails.aspx?regexp_id=625

You asked a couple of questions: 1. Yes, I do some calculations with
the numbers after they are entered; 2. Yes, I do need to modify the
regex to allow $ and ( ), I can figure this out, as well as how to do
the math for the totaling up, etc., I started this part already.

Just two questions:

1) Why did you use onkeyup?? I ask because I thought that one is
supposed to use onchange for testing values or doing something with
values, because I thought onkeyup catches every single keystroke, the
user would never finish typing the number.

2) What IS the best event for validating form field entries -- onblur,
onchange, onkeyup (I am posting this to the group too).

Thank you very much again.

:) tom

**Thomas 'PointedEars' Lahn** · Nov 28 '05, 12:05 PM

Re: How to modify this script to allow negative numbers??

RobG wrote:
[color=blue]
> <script type="text/javascript">
> //<![CDATA[[/color]

This is nonsense. Either you serve XHTML, then you should serve it as
application/xhtml+xml and need the declaration for easily legible inline
source code: user agents that support it, like Mozilla/5.0, will use their
faster XML parser that only accepts well-formed documents; user agents that
do not support it, like IE 6.x, will try to download it. Or you serve
HTML, then serve it as text/html where the tagsoup parser will be used and
CDATA declarations will have neither meaning nor will they be necessary
as the `script' element's content is PCDATA by default _only_ in XHTML.

The commented-out declaration was most certainly included in the attempt
to serve XHTML as text/html to achieve what XHTML 1.0, Appendix C, calls
"HTML compatibility". However, that section of the specification is
flawed; it is trying to achieve what cannot be achieved (since HTML and
XHTML are fundamentally different, especially in the meaning of the NET
delimiter), and it is potentially harmful since it relies solely on
afterwards non-specified error-correction by the user agent that, when
applied, _contradicted_ the HTML standard in this regard.

`<br />' in XHTML is `<br>>' in HTML, _not_ `<br>', and CDATA content
will end at the first `</' not at `]]>'.
[color=blue]
> [...]
> //]]>
> </script>[/color]

<URL:http://hixie.ch/advocacy/xhtml>

PointedEars

**RobG** · Nov 28 '05, 01:15 PM

Re: How to modify this script to allow negative numbers??

tlyczko wrote:[color=blue]
> Thank you for your help!!
>
> I am RE-learning Javascript as I go. You were right, it was a
> 1-year-old thread, I gambled and hopefully we have something here
> others can learn from.
>
> Merlyn's Javascript pages are wonderful but I find them sometimes
> rather abstract, because he uses a lot of includes to present things on
> his site and sometimes the demos etc. require the include files, so it
> can be a little difficult figuring out what to use.
>
> Thank you for the specific link, though. I missed it completely when I
> was reading his site before I found this script.
>
> A few hours after posting, I also found a great website,
> http://www.regexlib.com, which is a fantastic resource for regex
> patterns.
>
> I found one regex that although it is rather long, allows me to enter $
> and enclosing parentheses (and even commas), which are necessary for
> credits (to be subtracted) rather than debits (which will be added).
> Purchase requisitions rarely have credits, usually everything is added
> up.
>
> The link for the regex is
> http://www.regexlib.com/REDetails.aspx?regexp_id=625
>
> You asked a couple of questions: 1. Yes, I do some calculations with
> the numbers after they are entered; 2. Yes, I do need to modify the
> regex to allow $ and ( ), I can figure this out, as well as how to do
> the math for the totaling up, etc., I started this part already.
>
> Just two questions:
>
> 1) Why did you use onkeyup?? I ask because I thought that one is
> supposed to use onchange for testing values or doing something with
> values, because I thought onkeyup catches every single keystroke, the
> user would never finish typing the number.[/color]

I used keyup because that is what you posted code. As this seems like
an intranet application, you probably have users telling you what they
want. onblur will only fire when the focus moves on.

I just want you to be aware of the issues and can get your users to
pick what they want - implement it however you want. Often developers
force what they think should be done when the users have a much better
idea of the required functionality.

[color=blue]
>
> 2) What IS the best event for validating form field entries -- onblur,
> onchange, onkeyup (I am posting this to the group too).[/color]

Whatever your users like. If you use in-form error messages (like the
one I posted as an example but maybe you want to format it better)
then onkeyup is fine, just so long as the user's keystrokes aren't
affected. They see the message and can decide whether to ignore it or
not. Always keep the messages helpful and positive.

Check again on submit as they may have missed a message. :-)

--
Rob

**RobG** · Nov 28 '05, 01:15 PM

Re: How to modify this script to allow negative numbers??

Thomas 'PointedEars' Lahn wrote:[color=blue]
> RobG wrote:
>
>[color=green]
>><script type="text/javascript">
>>//<![CDATA[[/color]
>
>
> This is nonsense. Either you serve XHTML,[/color]

Talk to the OP Thomas.

[...]

--
Rob

**tlyczko** · Nov 28 '05, 02:45 PM

Re: How to modify this script to allow negative numbers??

Thank you, Thomas, for the comments about CDATA, though there was no
need to be so brusque.

RobG correctly observed this is an intranet app. However, it's on IE
6.x and someday later IE 7.x, so your "correct" way of serving the
document won't work for IE 6.x. It will become an included *.js file
anyway.

RobG, thank you again for your helpful answers...I will probably use
onchange as it is easier to understand initially, I have seen comments
about problems with onblur, and I don't yet understand the difference
between onchange and onblur, I need to read about this first.

I will try onkeyup too and see what happens, and I will use a simpler
regex / test mechanism than the code I posted at the beginning of this
thread.

Thank you again, everyone!!

:) tom

**Thomas 'PointedEars' Lahn** · Nov 28 '05, 03:05 PM

Re: How to modify this script to allow negative numbers??

tlyczko wrote:
[color=blue]
> Thank you, Thomas, for the comments about CDATA,
> though there was no need to be so brusque.[/color]

It was not the first time I explained it here.

PointedEars

**tlyczko** · Nov 28 '05, 03:15 PM

Re: How to modify this script to allow negative numbers??

Hi RobG (and anyone else who may know),

Thank you again for the sample code you provided above. For the most
part it does what I need it to do.

I tried out the sample code you gave me, it is very nice, onkeyup works
adequately, but how do I make the error message go away after they have
corrected the data input???

Should I add an onchange or onblur event with much the same code for
additional checking to see if the user has fixed the error???

I definitely should have the error message go away after they have
fixed it.

Thank you,
Tom

**tlyczko** · Nov 28 '05, 03:35 PM

Re: How to modify this script to allow negative numbers??

Note: I also found this website with these two links, which are going
to help me a lot.

Real's How-to

http://www.rgagnon.com/jsdetails/js-0063.html

Real's HowTo : Useful code snippets for Java, JS, PB and more

Easy Form Validation Using Regular Expressions

http://www.rgagnon.com/examples/jsregexp.html

Many useful regexp validations there, the only one missing is to allow
parentheses or negative numbers on currency values so they can be
"credits."

Thank you,
:) tom

**tlyczko** · Nov 28 '05, 03:35 PM

Re: How to modify this script to allow negative numbers??

I spoke too soon, the currency validator does allow adding parentheses
if one types a negative number, try the examples.

Thank you,
:) tom

**tlyczko** · Nov 28 '05, 03:55 PM

Re: How to modify this script to allow negative numbers??

I discovered that onkeypress fixes it for me, I just need to fix it so
if only one digit or no digits after the decimal place it shows the
error message, as well as allow minus signs.

Thank you,
:) tom

How to modify this script to allow negative numbers??

How to modify this script to allow negative numbers??

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