Subj : Re: regular expression
To   : Moe tokrot
From : Brendan Eich
Date : Tue May 18 2004 04:33 pm

Moe tokrot wrote:
> Hi,
> 
> I'm trying to use regExp in my application,
> It works fine for most patterns but i can't use the character '.'
> 
> 
> for example:
> 
>  char* regExp="var re=new RegExp(\"\\.\",\"g\");re.test(\"ghhfdhgh\");";
>   JS_EvaluateScript(cx, global, regExp, strlen(regExp), filename, lineto,
> &rval);
> 
> returns me true instead of false !!
> 
> i typed the same pattern (except that i didn't backquote the " characters)
> in the shell it works fine
> 
> I 'm stuck... if someone can help !


You really should use const char regExp[] = ..., not char*.

You should not use new RegExp here, it requires extra 
backslash-escaping, which you have failed to include.  Read the string 
from left to right, and from the "outside" in:

You gave the C compiler this string:
   "var re=new RegExp(\"\\.\",\"g\");re.test(\"ghhfdhgh\");"

The C compiler turned it into this string, without extra notation on my 
part:
   var re=new RegExp("\.","g");re.test("ghhfdhgh");

The JS engine compiles the first string, "\.", into this string:
   .

The JS engine therefore compiles a global regexp to match any character.

If you use regular expression literal notation, all is well, and a *lot* 
more readable:

"var re=/\\./g;re.test(\"ghhfdhgh\");"

/be

.