Regexp problem with form element

[Christoph]

I'm trying to set up client side validation for a textarea form element to
ensure that the data entered does not exceed 200 characters. I'm using the
following code but it doesn't seem to be working correctly:

if( this.value != '' ) {
if( !( RegExp( '^[.]{0,200}$' ).test( this.value ))) {
alert( 'Information provided must not be more than 200 characters.' );
this.focus();
}
}

I'm attaching the code to the OnBlur event. The test is passed if there is
no data in the text area. It fails if there is data, regardless of what
that data consists of. What's going on? I thought the dot matched any
character? Also, I've tried removing the beginning and ending ^$, but if I
do that then the test always seems to pass, even if the text is greater than
200 characters in length.

What am I doing wrong?

thnx,
Christoph

[Martin Honnen]

Christoph wrote:

I'm trying to set up client side validation for a textarea form element to
ensure that the data entered does not exceed 200 characters. I'm using the
following code but it doesn't seem to be working correctly:

if( this.value != '' ) {

if (this.value.length > 200) {
alert(...);
}
}

I don't think you need a regular expression to test the number of
characters.
--

Martin Honnen
http://JavaScript.FAQTs.com/

[Evertjan.]

Christoph wrote on 17 apr 2006 in comp.lang.javascript:

if( this.value != '' ) {
if( !( RegExp( '^[.]{0,200}$' ).test( this.value ))) {
alert( 'Information provided must not be more than 200 characters.' );
this.focus();
} }

simplified:

if (this.value.length>200) {
alert( 'Information provided must not be more than 200 characters.' );
this.focus();
}

--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

[Evertjan.]

Martin Honnen wrote on 17 apr 2006 in comp.lang.javascript:

Christoph wrote:

I'm trying to set up client side validation for a textarea form
element to ensure that the data entered does not exceed 200
characters. I'm using the following code but it doesn't seem to be
working correctly:

if( this.value != '' ) {

if (this.value.length > 200) {
alert(...);
}
}

I don't think you need a regular expression to test the number of
characters.

and why testing for zero length twice?
--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

[Lasse Reichstein Nielsen]

"Christoph" <jc*****@yahoo.com> writes:

I'm trying to set up client side validation for a textarea form element to
ensure that the data entered does not exceed 200 characters. if( this.value != '' ) {
if( !( RegExp( '^[.]{0,200}$' ).test( this.value ))) {
As Martin Honnen said, this.value.length is much more efficient.

The problem with your regexp, just for completeness, is that
the character class "[.]" matches exactly one ".", so you
check against strings of "."'s of length 0..200. What you would
have wanted, were you to use a regexp for this, is
RegExp('^.{0,200}$')
Actually, since you are using it on a textarea, which can contain
newlines, you don't want to use ".", since it only matches non-
newlines. Instead, you can use:
RegExp('^[\\s\\S]{0,200}$')

I also recommend using literal regexp notation. It saves on the
backslashes:
/^[\s\S]{0,200}$/
I'm attaching the code to the OnBlur event.
Dangerous. You are effectively preventing the user from having focus
leave the textarea. It's much more pleasent to be allowed to leave
fields invalid while you work on other fields. I recommend marking the
field as invalid somehow (red border, small warning icons, whatever
suits your page's style) and only preventing form submission by testing
in the form's onsubmit handler too.
The test is passed if there is no data in the text area. It fails
if there is data, regardless of what that data consists of.
Try with the string "....." :)
I thought the dot matched any character?

It does, on its own. Inside a character class ("[".."]") it has
no special meaning.

/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

[Christoph]

> I don't think you need a regular expression to test the number of

characters.

Indeed. It's definitely been one of those mondays. Thanks for
bringing me back down from overcomplication. :p

thnx,
Christoph

[Thomas 'PointedEars' Lahn]

Lasse Reichstein Nielsen wrote:

"Christoph" <jc*****@yahoo.com> writes:

I thought the dot matched any character?

It does, on its own. Inside a character class ("[".."]") it has
no special meaning.

Just for completeness, even standalone the dot does
not match any character. It does not match a newline
character.
PointedEars