Question

The regex is constructed on the fly, but I’ve output it to firebug:

(.{1,38})(+|$\n?)

the error is

invalid quantifier +|$\n?)

I’m not sure where to start.

The actual code is:

var re = top.RegExp;
var regex = new re("(.{1," + len + "})(+|$\\n?)", "gm");

UPDATE:
Per Bennor McCarthy’s instructions, I changed the code to this:

 var regex = new re("(.{1," + len + "})(\+|\$\\n?)", "gm");

Firebug still tells me this:

invalid quantifier +|$\n?)
[Break on this error] var regex = new re("(.{1," + len + "})(\+|\$\\n?)", "gm"); 

ANOTHER UPDATE
Looks Like I had to double slash it and this solved the problem!

final code

var regex = new re("(.{1," + len + "})(\\+|\\$\\n?)", "gm");

Answer 1

The problem is the +, which is a quantifier you need to escape.

Use this instead:

/(.{1,38})(\+|$\n?)/

or inside a string:

"(.{1,38})(\\+|$\\n?)"

If you want to match the literal $ followed by a newline, you need to escape the $ with \ (or \\ inside a string – see my last comment below this for an explanation).

Here’s some information on quantifiers.