Control Charcters In Form Input Field

In a form I have an input field. It's supposed to get input form a
scanning device. Thus, the input might contain special characters (like
the Group Separator in a EAN barcode). Now, I want to manipulate a
little with the input in a javascript, but I'm not able to find the
Group Separator:

input = document.main.input.value;
var a = input.split("");
var i;
for(i=0;i<a.length;i++) {
if(/x1D/.test(a[i])) {
alert("GS");
}
}

This is a snip that parses the input, character by character, and gives
me an alert if the Group Separator (Hex: 1D) is found. But it never
matches, even if I know that the input string contains in. I have a
similar script written in Perl, an that script finds the Group Separtor.

What can I do to find the %"#¤ Group Separator??