Regular expression breaks script execution

In javascript, when I wanto to get a bunch of specific folders, I use new RegExp(a,b) like this:

new RegExp (a, b)

a >> [String] my regular expression (don't use the / caracter before and after

b >> [String]  "g" or "i" or "gi", ...  (second argument is optional)

Example:

var myReg= new RegExp( "[^\_|a-zA-Z|0-9][A-Z][0-9]{8}$");
var all = Folder([myFolder]).getFiles(myReg).sort();

Another example I use (this one accepts all lower/uppercase letters:

var ID = 12345678;
var regthis = new RegExp( "((([x-z]{1}?)[a-v]{1}[_|c]{1})?)"+ID.toString(),"i");
var sameIDfolders = Folder([myFolder]).getFiles(regthis);

I don't know how you use this regex. Perhaps this easier variant can help you?

\w+(?=\..{2,4}$)

There are parts of RegExp that are not supported or are buggy in PS/JS. If it works in Firefox and/or elsewhere but not in PS/JS, you have to rewrite your regexp and file a bug support with Adobe. I've had problems like this in the past.

If you already have the string isolated, doing this will work as well: File(str).name then use a simpler regexp to strip off the extension.

For overkill, use this:

//========================= Filename formatting ===============================
//
// File.strf(fmt [, fs])
// Folder.strf(fmt [, fs])
//   This is based on the file name formatting facility in exiftool. Part of
//   the description is copied directly from there. You can find exiftool at:
//      http://www.sno.phy.queensu.ca/~phil/exiftool/
//
// Description:
//   Format a file string using a printf-like format string
//
// fmt is a string where the following substitutions occur
//   %d - the directory name (no trailing /)
//   %f - the file name without the extension
//   %e - the file extension without the leading '.'
//   %p - the name of the parent folder
//   %% - the '%' character
//
// if fs is true the folder is in local file system format
//   (e.g. C:\images instead of /c/images)
//
// Examples:
//
// Reformat the file name:
// var f = new File("/c/work/test.jpg");
// f.strf("%d/%f_%e.txt") == "/c/work/test_jpg.txt"
//
// Change the file extension
// f.strf("%d/%f.psd") == "/c/work/test.psd"
//
// Convert to a file name in a subdirectory named after the extension
// f.strf("%d/%e/%f.%e") == "/c/work/jpg/test.jpg"
//
// Change the file extension and convert to a file name in a subdirectory named
//   after the new extension
// f.strf("%d/psd/%f.psd") == "/c/work/psd/test.psd"
//
// var f = new File("~/.bashrc");
// f.strf("%f") == ".bashrc"
// f.strf("%e") == ""
//
// Advanced Substitution
//   A substring of the original file name, directory or extension may be
//   taken by specifying a string length immediately following the % character.
//   If the length is negative, the substring is taken from the end. The
//   substring position (characters to ignore at the start or end of the
//   string) may be given by a second optional value after a decimal point.
// For example:
//
// var f = new File("Picture-123.jpg");
//
// f.strf("%7f.psd") == "Picture.psd"
// f.strf("%-.4f.psd") == "Picture.psd"
// f.strf("%7f.%-3f") == "Picture.123"
// f.strf("Meta%-3.1f.xmp") == "Meta12.xmp"
//
File.prototype.strf = function(fmt, fs) {
  var self = this;
  var name = decodeURI(self.name);
  //var name = (self.name);

  // get the portions of the full path name

  // extension
  var m = name.match(/.+\.([^\.\/]+)$/);
  var e = m ? m[1] : '';

  // basename
  m = name.match(/(.+)\.[^\.\/]+$/);
  var f = m ? m[1] : name;

  fs |= !($.os.match(/windows/i)); // fs only matters on Windows
  // fs |= isMac();

  // full path...
  var d = decodeURI((fs ? self.parent.fsName : self.parent.absoluteURI));

  // parent directory...
  var p = decodeURI(self.parent.name);

  //var p = ((fs ? self.parent.fsName : self.parent.toString()));

  var str = fmt;

  // a regexp for the format specifiers

  var rex = /([^%]*)%(-)?(\d+)?(\.\d+)?(%|d|e|f|p)(.*)/;

  var result = '';

  while (m = rex.exec(str)) {
    var pre = m[1];
    var sig = m[2];
    var len = m[3];
    var ign = m[4];
    var typ = m[5];
    var post = m[6];

    var subst = '';

    if (typ == '%') {
      subst = '%';

    } else {
      var s = '';
      switch (typ) {
        case 'd': s = d; break;
        case 'e': s = e; break;
        case 'f': s = f; break;
        case 'p': s = p; break;
        // default: s = "%" + typ; break; // let others pass through
      }

      var strlen = s.length;

      if (strlen && (len || ign)) {
        ign = (ign ? Number(ign.slice(1)) : 0);
        if (len) {
          len = Number(len);
          if (sig) {
            var _idx = strlen - len - ign;
            subst = s.slice(_idx, _idx+len);
          } else {
            subst = s.slice(ign, ign+len);
          }
        } else {
          if (sig) {
            subst = s.slice(0, strlen-ign);
          } else {
            subst = s.slice(ign);
          }
        }

      } else {
        subst = s;
      }
    }

    result += pre + subst;
    str = post;
  }

  result += str;

  return result;
};
Folder.prototype.strf = File.prototype.strf;