Text form validation help needed

[Iain Downie]

Dear Group,

I have a text field that I wish to cellect numbers of bird seen. However,
some folk want to use 'c' before the number or '+' after to indicate a fuzzy
number. I have tried creating a function that checks for each of these and
still validates the rest as a number:

function checkNumber( an_item )
{
count_val = an_item.value;
len = count_val.length;
count = "";
if (count_val.charAt(0) == "c"){
count = count_val.substring(1,len);
} else if (count_val.charAt(len-1) == "+"){
count = count_val.substring(0,len-1);
} else {
count = count_val;
}
if (isNaN (count)) {
msg = "Error: " + count + " is not a valid number for the Count
field";
alert (msg);
an_item.value = "";
return false;
} else {
count_num = parseInt (count);
if ((count_num < 1) || (count_num > 999999)) {
msg = "Error: The number in the Count field must be\nbetween 1 and
999,999";
alert (msg);
an_item.value = "";
return false;
}
}
}
This seems to work if I enter c1000 and 1000+ birds (both accepted), and
also if I enter ca1000 it catches that. But, it seems to accept +1000 and I
can't explain why. Any takers for an improvement? For info, I'll be handling
the 'c' and '+' later, but I just need to make sure it is only these options
(other than a pure number) that come through.

Thanks
Iain
--

__________________________________________________ _________
Iain Downie
British Trust for Ornithology, The Nunnery,
Thetford, Norfolk IP24 2PU, UK ® Charity No. 216652
Tel: [phone], fax: [phone]
BirdWeb Gateway: http://www.bto.org/birdweb

[Ivo]

"Iain Downie" wrote

I have a text field that I wish to cellect numbers of bird seen. However,
some folk want to use 'c' before the number or '+' after to indicate a
fuzzy number. I have tried creating a function that checks for each of
these and still validates the rest as a number:

function checkNumber( an_item )
{
count_val = an_item.value;
len = count_val.length;
count = "";
if (count_val.charAt(0) == "c"){
<snip code>

This seems to work if I enter c1000 and 1000+ birds (both accepted), and
also if I enter ca1000 it catches that. But, it seems to accept +1000 and
I can't explain why. Any takers for an improvement? For info, I'll be
handling the 'c' and '+' later, but I just need to make sure it is only
these options (other than a pure number) that come through.

A regex might be an idea. In the following example, spaces between the
number and either the c or the + are allowed, so "c 99" will validate. If
you don't want this, remove the two occurances of " \s* " in the code below.

function checkNumber( an_item ) {
count_val = an_item.value;
x = count_val.match(/(^c?\s*(\d+)$)|(^(\d+)\s*\+?$)/);
if(!x)
{ alert('Please keep to the right format.'); return false;}
else if(x[2]<1||x[2]>999999)
{ alert('Please enter a number below 999999.'); return false;}
return true;
}
HTH
Ivo

[Mick White]

Iain Downie wrote:

Dear Group,

I have a text field that I wish to cellect numbers of bird seen. However,
some folk want to use 'c' before the number or '+' after to indicate a fuzzy
number. I have tried creating a function that checks for each of these and
still validates the rest as a number:

function checkNumber( an_item ) function checkNumber( an_item ){
// You can get count from "an_item" and check that its between 1 & 999999

count=Number("an_item.value".replace(/[^\d]/g,""));
if(!count){alert("No number entered"); return false;}
if(count>999999) {alert("Too many"); return false;}
// This doesn't check for "c" or "+" though, a simple
// regex will do that, but will return true
// if a number (1-999999)is entered.
// You may want to store "count" in hidden field:

an_item.form.hiddenFieldName.value=count;
return true;
}

Mick

{
count_val = an_item.value;
len = count_val.length;
count = "";
if (count_val.charAt(0) == "c"){
count = count_val.substring(1,len);
} else if (count_val.charAt(len-1) == "+"){
count = count_val.substring(0,len-1);
} else {
count = count_val;
}
if (isNaN (count)) {
msg = "Error: " + count + " is not a valid number for the Count
field";
alert (msg);
an_item.value = "";
return false;
} else {
count_num = parseInt (count);
if ((count_num < 1) || (count_num > 999999)) {
msg = "Error: The number in the Count field must be\nbetween 1 and
999,999";
alert (msg);
an_item.value = "";
return false;
}
}
}
This seems to work if I enter c1000 and 1000+ birds (both accepted), and
also if I enter ca1000 it catches that. But, it seems to accept +1000 and I
can't explain why. Any takers for an improvement? For info, I'll be handling
the 'c' and '+' later, but I just need to make sure it is only these options
(other than a pure number) that come through.

Thanks
Iain
--

__________________________________________________ _________
Iain Downie
British Trust for Ornithology, The Nunnery,
Thetford, Norfolk IP24 2PU, UK ® Charity No. 216652
Tel: [phone], fax: [phone]
BirdWeb Gateway: http://www.bto.org/birdweb

[Dr John Stockton]

JRS: In article <cd*******************@news.demon.co.uk>, seen in
news:comp.lang.javascript, Iain Downie <ia*********@bto.org> posted at
Thu, 15 Jul 2004 17:24:54 :

I have a text field that I wish to cellect numbers of bird seen. However,
some folk want to use 'c' before the number or '+' after to indicate a fuzzy
number. I have tried creating a function that checks for each of these and
still validates the rest as a number: count_num = parseInt (count);

Read the FAQ. That code will silently give the wrong number if someone
enters, say, 077. Generally, parseInt is used far more often than is
necessary; and often wrongly.

Signatures should not exceed four lines after a separator line minus
minus space. No-one reasonable would complain about your five text
lines, but the three empty lines and the rule are unnecessary.

AFAICS, it is *always* best to validate input with a RegExp - see
<URL:http://www.merlyn.demon.co.uk/js-valid.htm>. In this case, you can
use ([1-9]\d{0,5}) as part of the RegExp - that means all-digit,
compulsory first digit 1-9, digit count 1-6; so there is no need to test
arithmetically.

OK = /^(c?)([1-9]\d{0,5})(\+?)$/.test(count_val)
if (!OK) { alert{"Blunder") ; ... }
count_num = +RegExp.$2 // number
Roughly = !!( RegExp.$1 + RegExp.$3 ) // boolean

That allows c before and/or + after. The !! is not-not, and forces
Boolean conversion; IIRC, an empty string -> false and a non-empty ->
true.

If you have a thousands separator in a message, you should allow one in
the data; best omit.

Would "?" be better as a fuzzy indicator? Note that 'c' means 'circa'
means "about" and '+' means 'over'; they can be interpreted differently
by testing $1 & $3 separately.

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4 ©
<URL:http://jibbering.com/faq/> JL / RC : FAQ for news:comp.lang.javascript
<URL:http://www.merlyn.demon.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demon.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.

[Iain Downie]

Ivo

A regex might be an idea. In the following example, spaces between the
number and either the c or the + are allowed, so "c 99" will validate. If
you don't want this, remove the two occurances of " \s* " in the code below.
function checkNumber( an_item ) {
count_val = an_item.value;
x = count_val.match(/(^c?\s*(\d+)$)|(^(\d+)\s*\+?$)/);
if(!x)
{ alert('Please keep to the right format.'); return false;}
else if(x[2]<1||x[2]>999999)
{ alert('Please enter a number below 999999.'); return false;}
return true;
}

Unfortunately this code pulls up the alert 'number below 999999' error if I
enter 1000+. I need both c1000 and 1000+ to be valid, or just 1000.

I have a problem with regex code snippets in general - I have no idea how
they work so unable to adapt it!! However, It looks much more efficient. I
suppose I should learn, never seem to have the time.

Iain

[Iain Downie]

"Dr John Stockton" <sp**@merlyn.demon.co.uk> wrote in message
news:C2**************@merlyn.demon.co.uk...

JRS: In article <cd*******************@news.demon.co.uk>, seen in
news:comp.lang.javascript, Iain Downie <ia*********@bto.org> posted at
Thu, 15 Jul 2004 17:24:54 :
Signatures should not exceed four lines after a separator line minus
minus space. No-one reasonable would complain about your five text
lines, but the three empty lines and the rule are unnecessary.
Fair point. Will reduce.

Would "?" be better as a fuzzy indicator? Note that 'c' means 'circa'
means "about" and '+' means 'over'; they can be interpreted differently
by testing $1 & $3 separately.

Unfortunately, these are the two values that birdwatchers use, and yes, they
are meant to be differently interpreted. Our population trend stats will not
use this really, it is purely a personal record for folk entering records
online.

Iain