REGEX Javascript

var response = "0.00";
var regularExpression = "" + tag + "([\\s\\S]*?)\\/" + tag + "";
try {
    var status = new RegExp(regularExpression, "gm");
    response = status.exec(input)[1];
} catch (e) {
    return "null";
}
if (response.charAt(0)=="-")
{
    return "-" + prefix + response.substring(response.length-1,1);
}
else
{
    return prefix + response;
}