Variable inside RegEx

[Er Galv?o Abbott]

Greetings.

I have a function that does some pattern matching with JS's RegEx and
I'm trying to use a variable inside of it. Nothing that I've done
worked, so please help me.

Here is the func:

function validateField(f ormField,limit)
{
if (formField.matc h(/^\d{1,11}\,\d{2 }$/))
{
return true;
}
}

What I need is to replace the "11" in the RegEx with the var limit.

How can I do this???

TIA,

[Michael Winter]

Re: Variable inside RegEx

On 16 Feb 2004 09:19:00 -0800, Er Galv?o Abbott <galvao@galvao. eti.br>
wrote:
[color=blue]
> Greetings.
>
> I have a function that does some pattern matching with JS's RegEx and
> I'm trying to use a variable inside of it. Nothing that I've done
> worked, so please help me.
>
> Here is the func:
>
> function validateField(f ormField,limit)
> {
> if (formField.matc h(/^\d{1,11}\,\d{2 }$/))
> {
> return true;
> }
> }
>
> What I need is to replace the "11" in the RegEx with the var limit.
>
> How can I do this???[/color]

As you've no doubt discovered, literals cannot have variables in them.
However, the RegExp() constructor can:

function validateField( formField, limit ) {
var re = new RegExp( '^\d{1,' + limit + '}\,\d{2}$' );

return formField.match ( re );
}

If you need to use flags, add them as a string as the second parameter.
Global, for example:

... = new RegExp( 'pattern', 'g' );

Hope that helps,
Mike

--
Michael Winter
M.Winter@blueyo nder.co.invalid (replace ".invalid" with ".uk" to reply)

[Lasse Reichstein Nielsen]

Re: Variable inside RegEx

galvao@galvao.e ti.br (Er Galv?o Abbott) writes:
[color=blue]
> if (formField.matc h(/^\d{1,11}\,\d{2 }$/))[/color]

(no need to escape the comma)
[color=blue]
> What I need is to replace the "11" in the RegEx with the var limit.[/color]

If the regular expression isn't constant, you can't use the literal
notation, and must construct the regular expression using the RegExp
function instead.

RegExp("^\\d{1, " + limit + "},\\d{2}$" )

Notice that the argument to RegExp is a string literal, and as such
treats backslashes special. To include a backslash in the generated
regular expression, you must write two in the string literal.

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

[Richard Cornford]

Re: Variable inside RegEx

"Michael Winter" <M.Winter@bluey onder.co.invali d> wrote in message
news:opr3g5hdvj 5vklcq@news-text.blueyonder .co.uk...
<snip>[color=blue]
> function validateField( formField, limit ) {
> var re = new RegExp( '^\d{1,' + limit + '}\,\d{2}$' );[/color]
<snip>

But is necessary to escape the escape characters in the string literals
provided for the RegExp constructor, something like (untested):-

var re = new RegExp( '^\\d{1,' + limit + '}\\,\\d{2}$' );

Richard.

[Michael Winter]

Re: Variable inside RegEx

On Mon, 16 Feb 2004 18:39:59 -0000, Richard Cornford
<Richard@litote s.demon.co.uk> wrote:
[color=blue]
> "Michael Winter" <M.Winter@bluey onder.co.invali d> wrote in message
> news:opr3g5hdvj 5vklcq@news-text.blueyonder .co.uk...
> <snip>[color=green]
>> function validateField( formField, limit ) {
>> var re = new RegExp( '^\d{1,' + limit + '}\,\d{2}$' );[/color]
> <snip>
>
> But is necessary to escape the escape characters in the string literals
> provided for the RegExp constructor, something like (untested):-[/color]

[snipped example]

*Slaps forehead*

Quite right.

Mike

--
Michael Winter
M.Winter@blueyo nder.co.invalid (replace ".invalid" with ".uk" to reply)